Selecting a CSI-RS for a Random Access Procedure of a Cell

ABSTRACT

A base station receives, from a wireless device, at least one first measurement report of at least one synchronization signal of a cell. One or more channel state information reference signals (CSI-RSs) of the cell are selected based on: the at least one first measurement report; and a first antenna port of the one or more CSI-RSs being quasi-collocated with a second port of the at least one synchronization signal. At least one second measurement report of the one or more CSI-RSs is received. At least one first CSI-RS of the one or more CSI-RSs is selected based on the at least one second measurement report. A downlink control information initiating a random access procedure of the cell is transmitted. The random access procedure is based on the at least one first CSI-RS.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/101,132, filed Aug. 10, 2018, which claims the benefit of U.S.Provisional Application No. 62/543,835, filed Aug. 10, 2017, which arehereby incorporated by reference in its entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present inventionare described herein with reference to the drawings.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present disclosure.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers in a carrier group as per an aspect of anembodiment of the present disclosure.

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present disclosure.

FIG. 4 is a block diagram of a base station and a wireless device as peran aspect of an embodiment of the present disclosure.

FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present disclosure.

FIG. 6 is an example diagram for a protocol structure withmulti-connectivity as per an aspect of an embodiment of the presentdisclosure.

FIG. 7 is an example diagram for a protocol structure with CA and DC asper an aspect of an embodiment of the present disclosure.

FIG. 8 shows example TAG configurations as per an aspect of anembodiment of the present disclosure.

FIG. 9 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentdisclosure.

FIG. 10A and FIG. 10B are example diagrams for interfaces between a 5Gcore network (e.g. NGC) and base stations (e.g. gNB and eLTE eNB) as peran aspect of an embodiment of the present disclosure.

FIG. 11A, FIG. 11B, FIG. 11C, FIG. 11D, FIG. 11E, and FIG. 11F areexample diagrams for architectures of tight interworking between 5G RAN(e.g. gNB) and LTE RAN (e.g. (e)LTE eNB) as per an aspect of anembodiment of the present disclosure.

FIG. 12A, FIG. 12B, and FIG. 12C are example diagrams for radio protocolstructures of tight interworking bearers as per an aspect of anembodiment of the present disclosure.

FIG. 13A and FIG. 13B are example diagrams for gNB deployment scenariosas per an aspect of an embodiment of the present disclosure.

FIG. 14 is an example diagram for functional split option examples ofthe centralized gNB deployment scenario as per an aspect of anembodiment of the present disclosure.

FIG. 15A and FIG. 15B are examples of a contention-based four-step RAprocedure and contention free RA procedure as per an aspect of anembodiment of the present disclosure.

FIG. 16 is an example MAC PDU format of an example of MAC PDU comprisinga MAC header and MAC RARs for four-step RA procedure as per an aspect ofan embodiment of the present disclosure.

FIG. 17A, FIG. 17B, and FIG. 17C are example MAC RAR formats as per anaspect of an embodiment of the present disclosure.

FIG. 18 is an example of the RA procedure comprising broadcastingmultiple SS blocks as per an aspect of an embodiment of the presentdisclosure.

FIG. 19 is an example of RACH Occasion, RACH Burst and RACH Burst Set asper an aspect of an embodiment of the present disclosure.

FIG. 20A, FIG. 20B, and FIG. 20C are examples of TDM and FDM mapping ofPRACH resources as per an aspect of an embodiment of the presentdisclosure.

FIG. 21 is an example of RA procedure with multi-beam as per an aspectof an embodiment of the present disclosure; a UE detects the second SSblocks and thereby transmits a preamble on a RACH resource correspondingto the second SS block to inform gNB of the preferred beam. gNB respondswith a RAR using the beam that the UE prefers.

FIG. 22A and FIG. 22B are examples of one or more beams configured withSS block (FIG. 22A) and CSI-RS (FIG. 22B) as per an aspect of anembodiment of the present disclosure.

FIG. 23A and FIG. 23B are examples of mapping beam specific preambles toPRACH occasion: FIG. 23A is an example of one-to-one mapping and FIG.23B is an example of k-to-one mapping as per an aspect of an embodimentof the present disclosure.

FIG. 24 is an example of beam refinement procedure as per an aspect ofan embodiment of the present disclosure.

FIG. 25 is an example of beam refinement procedure as per an aspect ofan embodiment of the present disclosure.

FIG. 26 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 27 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 28 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

FIG. 29 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the present invention enable operation of carrieraggregation. Embodiments of the technology disclosed herein may beemployed in the technical field of multicarrier communication systems.More particularly, the embodiments of the technology disclosed hereinmay relate to signal timing in a multicarrier communication systems.

The following Acronyms are used throughout the present disclosure:

-   -   ASIC application-specific integrated circuit    -   BPSK binary phase shift keying    -   CA carrier aggregation    -   CSI channel state information    -   CDMA code division multiple access    -   CSS common search space    -   CPLD complex programmable logic devices    -   CC component carrier    -   CP cyclic prefix    -   DL downlink    -   DCI downlink control information    -   DC dual connectivity    -   eMBB enhanced mobile broadband    -   EPC evolved packet core    -   E-UTRAN evolved-universal terrestrial radio access network    -   FPGA field programmable gate arrays    -   FDD frequency division multiplexing    -   HDL hardware description languages    -   HARQ hybrid automatic repeat request    -   IE information element    -   LTE long term evolution    -   MCG master cell group    -   MeNB master evolved node B    -   MIB master information block    -   MAC media access control    -   MAC media access control    -   MME mobility management entity    -   mMTC massive machine type communications    -   NAS non-access stratum    -   NR new radio    -   OFDM orthogonal frequency division multiplexing    -   PDCP packet data convergence protocol    -   PDU packet data unit    -   PHY physical    -   PDCCH physical downlink control channel    -   PHICH physical HARQ indicator channel    -   PUCCH physical uplink control channel    -   PUSCH physical uplink shared channel    -   PCell primary cell    -   PCell primary cell    -   PCC primary component carrier    -   PSCell primary secondary cell    -   pTAG primary timing advance group    -   QAM quadrature amplitude modulation    -   QPSK quadrature phase shift keying    -   RBG resource block groups    -   RLC radio link control    -   RRC radio resource control    -   RA random access    -   RB resource blocks    -   SCC secondary component carrier    -   SCell secondary cell    -   Scell secondary cells    -   SCG secondary cell group    -   SeNB secondary evolved node B    -   sTAGs secondary timing advance group    -   SDU service data unit    -   S-GW serving gateway    -   SRB signaling radio bearer    -   SC-OFDM single carrier-OFDM    -   SFN system frame number    -   SIB system information block    -   TAI tracking area identifier    -   TAT time alignment timer    -   TDD time division duplexing    -   TDMA time division multiple access    -   TA timing advance    -   TAG timing advance group    -   TTI transmission time interval    -   TB transport block    -   UL uplink    -   UE user equipment    -   URLLC ultra-reliable low-latency communications    -   VHDL VHSIC hardware description language    -   CU central unit    -   DU distributed unit    -   Fs-C Fs-control plane    -   Fs-U Fs-user plane    -   gNB next generation node B    -   NGC next generation core    -   NG CP next generation control plane core    -   NG-C NG-control plane    -   NG-U NG-user plane    -   NR new radio    -   NR MAC new radio MAC    -   NR PHY new radio physical    -   NR PDCP new radio PDCP    -   NR RLC new radio RLC    -   NR RRC new radio RRC    -   NSSAI network slice selection assistance information    -   PLMN public land mobile network    -   UPGW user plane gateway    -   Xn-C Xn-control plane    -   Xn-U Xn-user plane    -   Xx-C Xx-control plane    -   Xx-U Xx-user plane

Example embodiments of the invention may be implemented using variousphysical layer modulation and transmission mechanisms. Exampletransmission mechanisms may include, but are not limited to: CDMA, OFDM,TDMA, Wavelet technologies, and/or the like. Hybrid transmissionmechanisms such as TDMA/CDMA, and OFDM/CDMA may also be employed.Various modulation schemes may be applied for signal transmission in thephysical layer. Examples of modulation schemes include, but are notlimited to: phase, amplitude, code, a combination of these, and/or thelike. An example radio transmission method may implement QAM using BPSK,QPSK, 16-QAM, 64-QAM, 256-QAM, and/or the like. Physical radiotransmission may be enhanced by dynamically or semi-dynamically changingthe modulation and coding scheme depending on transmission requirementsand radio conditions.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present disclosure. As illustrated inthis example, arrow(s) in the diagram may depict a subcarrier in amulticarrier OFDM system. The OFDM system may use technology such asOFDM technology, DFTS-OFDM, SC-OFDM technology, or the like. Forexample, arrow 101 shows a subcarrier transmitting information symbols.FIG. 1 is for illustration purposes, and a typical multicarrier OFDMsystem may include more subcarriers in a carrier. For example, thenumber of subcarriers in a carrier may be in the range of 10 to 10,000subcarriers. FIG. 1 shows two guard bands 106 and 107 in a transmissionband. As illustrated in FIG. 1, guard band 106 is between subcarriers103 and subcarriers 104. The example set of subcarriers A 102 includessubcarriers 103 and subcarriers 104. FIG. 1 also illustrates an exampleset of subcarriers B 105. As illustrated, there is no guard band betweenany two subcarriers in the example set of subcarriers B 105. Carriers ina multicarrier OFDM communication system may be contiguous carriers,non-contiguous carriers, or a combination of both contiguous andnon-contiguous carriers.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers as per an aspect of an embodiment of the presentdisclosure. A multicarrier OFDM communication system may include one ormore carriers, for example, ranging from 1 to 10 carriers. Carrier A 204and carrier B 205 may have the same or different timing structures.Although FIG. 2 shows two synchronized carriers, carrier A 204 andcarrier B 205 may or may not be synchronized with each other. Differentradio frame structures may be supported for FDD and TDD duplexmechanisms. FIG. 2 shows an example FDD frame timing. Downlink anduplink transmissions may be organized into radio frames 201. In thisexample, radio frame duration is 10 msec. Other frame durations, forexample, in the range of 1 to 100 msec may also be supported. In thisexample, each 10 ms radio frame 201 may be divided into ten equallysized subframes 202. Other subframe durations such as including 0.5msec, 1 msec, 2 msec, and 5 msec may also be supported. Subframe(s) maycomprise of two or more slots (e.g. slots 206 and 207). For the exampleof FDD, 10 subframes may be available for downlink transmission and 10subframes may be available for uplink transmissions in each 10 msinterval. Uplink and downlink transmissions may be separated in thefrequency domain. A slot may be 7 or 14 OFDM symbols for the samesubcarrier spacing of up to 60 kHz with normal CP. A slot may be 14 OFDMsymbols for the same subcarrier spacing higher than 60 kHz with normalCP. A slot may contain all downlink, all uplink, or a downlink part andan uplink part and/or alike. Slot aggregation may be supported, e.g.,data transmission may be scheduled to span one or multiple slots. In anexample, a mini-slot may start at an OFDM symbol in a subframe. Amini-slot may have a duration of one or more OFDM symbols. Slot(s) mayinclude a plurality of OFDM symbols 203. The number of OFDM symbols 203in a slot 206 may depend on the cyclic prefix length and subcarrierspacing.

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present disclosure. The resource grid structure intime 304 and frequency 305 is illustrated in FIG. 3. The quantity ofdownlink subcarriers or RBs may depend, at least in part, on thedownlink transmission bandwidth 306 configured in the cell. The smallestradio resource unit may be called a resource element (e.g. 301).Resource elements may be grouped into resource blocks (e.g. 302).Resource blocks may be grouped into larger radio resources calledResource Block Groups (RBG) (e.g. 303). The transmitted signal in slot206 may be described by one or several resource grids of a plurality ofsubcarriers and a plurality of OFDM symbols. Resource blocks may be usedto describe the mapping of certain physical channels to resourceelements. Other pre-defined groupings of physical resource elements maybe implemented in the system depending on the radio technology. Forexample, 24 subcarriers may be grouped as a radio block for a durationof 5 msec. In an illustrative example, a resource block may correspondto one slot in the time domain and 180 kHz in the frequency domain (for15 KHz subcarrier bandwidth and 12 subcarriers).

In an example embodiment, multiple numerologies may be supported. In anexample, a numerology may be derived by scaling a basic subcarrierspacing by an integer N. In an example, scalable numerology may allow atleast from 15 kHz to 480 kHz subcarrier spacing. The numerology with 15kHz and scaled numerology with different subcarrier spacing with thesame CP overhead may align at a symbol boundary every 1 ms in a NRcarrier.

FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present disclosure. FIG. 5A shows an example uplink physicalchannel. The baseband signal representing the physical uplink sharedchannel may perform the following processes. These functions areillustrated as examples and it is anticipated that other mechanisms maybe implemented in various embodiments. The functions may comprisescrambling, modulation of scrambled bits to generate complex-valuedsymbols, mapping of the complex-valued modulation symbols onto one orseveral transmission layers, transform precoding to generatecomplex-valued symbols, precoding of the complex-valued symbols, mappingof precoded complex-valued symbols to resource elements, generation ofcomplex-valued time-domain DFTS-OFDM/SC-FDMA signal for an antenna port,and/or the like.

Example modulation and up-conversion to the carrier frequency of thecomplex-valued DFTS-OFDM/SC-FDMA baseband signal for an antenna portand/or the complex-valued PRACH baseband signal is shown in FIG. 5B.Filtering may be employed prior to transmission.

An example structure for Downlink Transmissions is shown in FIG. 5C. Thebaseband signal representing a downlink physical channel may perform thefollowing processes. These functions are illustrated as examples and itis anticipated that other mechanisms may be implemented in variousembodiments. The functions include scrambling of coded bits in codewordsto be transmitted on a physical channel; modulation of scrambled bits togenerate complex-valued modulation symbols; mapping of thecomplex-valued modulation symbols onto one or several transmissionlayers; precoding of the complex-valued modulation symbols on a layerfor transmission on the antenna ports; mapping of complex-valuedmodulation symbols for an antenna port to resource elements; generationof complex-valued time-domain OFDM signal for an antenna port, and/orthe like.

Example modulation and up-conversion to the carrier frequency of thecomplex-valued OFDM baseband signal for an antenna port is shown in FIG.5D. Filtering may be employed prior to transmission.

FIG. 4 is an example block diagram of a base station 401 and a wirelessdevice 406, as per an aspect of an embodiment of the present disclosure.A communication network 400 may include at least one base station 401and at least one wireless device 406. The base station 401 may includeat least one communication interface 402, at least one processor 403,and at least one set of program code instructions 405 stored innon-transitory memory 404 and executable by the at least one processor403. The wireless device 406 may include at least one communicationinterface 407, at least one processor 408, and at least one set ofprogram code instructions 410 stored in non-transitory memory 409 andexecutable by the at least one processor 408. Communication interface402 in base station 401 may be configured to engage in communicationwith communication interface 407 in wireless device 406 via acommunication path that includes at least one wireless link 411.Wireless link 411 may be a bi-directional link. Communication interface407 in wireless device 406 may also be configured to engage in acommunication with communication interface 402 in base station 401. Basestation 401 and wireless device 406 may be configured to send andreceive data over wireless link 411 using multiple frequency carriers.According to some of the various aspects of embodiments, transceiver(s)may be employed. A transceiver is a device that includes both atransmitter and receiver. Transceivers may be employed in devices suchas wireless devices, base stations, relay nodes, and/or the like.Example embodiments for radio technology implemented in communicationinterface 402, 407 and wireless link 411 are illustrated are FIG. 1,FIG. 2, FIG. 3, FIG. 5, and associated text.

An interface may be a hardware interface, a firmware interface, asoftware interface, and/or a combination thereof. The hardware interfacemay include connectors, wires, electronic devices such as drivers,amplifiers, and/or the like. A software interface may include codestored in a memory device to implement protocol(s), protocol layers,communication drivers, device drivers, combinations thereof, and/or thelike. A firmware interface may include a combination of embeddedhardware and code stored in and/or in communication with a memory deviceto implement connections, electronic device operations, protocol(s),protocol layers, communication drivers, device drivers, hardwareoperations, combinations thereof, and/or the like.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayalso refer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics inthe device, whether the device is in an operational or non-operationalstate.

According to some of the various aspects of embodiments, a 5G networkmay include a multitude of base stations, providing a user plane NRPDCP/NR RLC/NR MAC/NR PHY and control plane (NR RRC) protocolterminations towards the wireless device. The base station(s) may beinterconnected with other base station(s) (e.g. employing an Xninterface). The base stations may also be connected employing, forexample, an NG interface to an NGC. FIG. 10A and FIG. 10B are examplediagrams for interfaces between a 5G core network (e.g. NGC) and basestations (e.g. gNB and eLTE eNB) as per an aspect of an embodiment ofthe present disclosure. For example, the base stations may beinterconnected to the NGC control plane (e.g. NG CP) employing the NG-Cinterface and to the NGC user plane (e.g. UPGW) employing the NG-Uinterface. The NG interface may support a many-to-many relation between5G core networks and base stations.

A base station may include many sectors for example: 1, 2, 3, 4, or 6sectors. A base station may include many cells, for example, rangingfrom 1 to 50 cells or more. A cell may be categorized, for example, as aprimary cell or secondary cell. At RRC connectionestablishment/re-establishment/handover, one serving cell may providethe NAS (non-access stratum) mobility information (e.g. TAI), and at RRCconnection re-establishment/handover, one serving cell may provide thesecurity input. This cell may be referred to as the Primary Cell(PCell). In the downlink, the carrier corresponding to the PCell may bethe Downlink Primary Component Carrier (DL PCC), while in the uplink, itmay be the Uplink Primary Component Carrier (UL PCC). Depending onwireless device capabilities, Secondary Cells (SCells) may be configuredto form together with the PCell a set of serving cells. In the downlink,the carrier corresponding to an SCell may be a Downlink SecondaryComponent Carrier (DL SCC), while in the uplink, it may be an UplinkSecondary Component Carrier (UL SCC). An SCell may or may not have anuplink carrier.

A cell, comprising a downlink carrier and optionally an uplink carrier,may be assigned a physical cell ID and a cell index. A carrier (downlinkor uplink) may belong to only one cell. The cell ID or Cell index mayalso identify the downlink carrier or uplink carrier of the cell(depending on the context it is used). In the specification, cell ID maybe equally referred to a carrier ID, and cell index may be referred tocarrier index. In implementation, the physical cell ID or cell index maybe assigned to a cell. A cell ID may be determined using asynchronization signal transmitted on a downlink carrier. A cell indexmay be determined using RRC messages. For example, when thespecification refers to a first physical cell ID for a first downlinkcarrier, the specification may mean the first physical cell ID is for acell comprising the first downlink carrier. The same concept may applyto, for example, carrier activation. When the specification indicatesthat a first carrier is activated, the specification may equally meanthat the cell comprising the first carrier is activated.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in a wireless device, a base station, a radio environment, a network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, traffic load, initial systemset up, packet sizes, traffic characteristics, a combination of theabove, and/or the like. When the one or more criteria are met, variousexample embodiments may be applied. Therefore, it may be possible toimplement example embodiments that selectively implement disclosedprotocols.

A base station may communicate with a mix of wireless devices. Wirelessdevices may support multiple technologies, and/or multiple releases ofthe same technology. Wireless devices may have some specificcapability(ies) depending on its wireless device category and/orcapability(ies). A base station may comprise multiple sectors. When thisdisclosure refers to a base station communicating with a plurality ofwireless devices, this disclosure may refer to a subset of the totalwireless devices in a coverage area. This disclosure may refer to, forexample, a plurality of wireless devices of a given LTE or 5G releasewith a given capability and in a given sector of the base station. Theplurality of wireless devices in this disclosure may refer to a selectedplurality of wireless devices, and/or a subset of total wireless devicesin a coverage area which perform according to disclosed methods, and/orthe like. There may be a plurality of wireless devices in a coveragearea that may not comply with the disclosed methods, for example,because those wireless devices perform based on older releases of LTE or5G technology.

FIG. 6 and FIG. 7 are example diagrams for protocol structure with CAand multi-connectivity as per an aspect of an embodiment of the presentdisclosure. NR may support multi-connectivity operation whereby amultiple RX/TX UE in RRC_CONNECTED may be configured to utilize radioresources provided by multiple schedulers located in multiple gNBsconnected via a non-ideal or ideal backhaul over the Xn interface. gNBsinvolved in multi-connectivity for a certain UE may assume two differentroles: a gNB may either act as a master gNB or as a secondary gNB. Inmulti-connectivity, a UE may be connected to one master gNB and one ormore secondary gNBs. FIG. 7 illustrates one example structure for the UEside MAC entities when a Master Cell Group (MCG) and a Secondary CellGroup (SCG) are configured, and it may not restrict implementation.Media Broadcast Multicast Service (MBMS) reception is not shown in thisfigure for simplicity.

In multi-connectivity, the radio protocol architecture that a particularbearer uses may depend on how the bearer is setup. Three examples ofbearers, including, an MCG bearer, an SCG bearer and a split bearer asshown in FIG. 6. NR RRC may be located in master gNB and SRBs may beconfigured as a MCG bearer type and may use the radio resources of themaster gNB. Multi-connectivity may also be described as having at leastone bearer configured to use radio resources provided by the secondarygNB. Multi-connectivity may or may not be configured/implemented inexample embodiments of the disclosure.

In the case of multi-connectivity, the UE may be configured withmultiple NR MAC entities: one NR MAC entity for master gNB, and other NRMAC entities for secondary gNBs. In multi-connectivity, the configuredset of serving cells for a UE may comprise of two subsets: the MasterCell Group (MCG) containing the serving cells of the master gNB, and theSecondary Cell Groups (SCGs) containing the serving cells of thesecondary gNBs. For a SCG, one or more of the following may be applied:at least one cell in the SCG has a configured UL CC and one of them,named PSCell (or PCell of SCG, or sometimes called PCell), is configuredwith PUCCH resources; when the SCG is configured, there may be at leastone SCG bearer or one Split bearer; upon detection of a physical layerproblem or a random access problem on a PSCell, or the maximum number ofNR RLC retransmissions has been reached associated with the SCG, or upondetection of an access problem on a PSCell during a SCG addition or aSCG change: a RRC connection re-establishment procedure may not betriggered, UL transmissions towards cells of the SCG are stopped, amaster gNB may be informed by the UE of a SCG failure type, for splitbearer, the DL data transfer over the master gNB is maintained; the NRRLC AM bearer may be configured for the split bearer; like PCell, PSCellmay not be de-activated; PSCell may be changed with a SCG change (e.g.with security key change and a RACH procedure); and/or a direct bearertype change between a Split bearer and a SCG bearer or simultaneousconfiguration of a SCG and a Split bearer may or may not supported.

With respect to the interaction between a master gNB and secondary gNBsfor multi-connectivity, one or more of the following principles may beapplied: the master gNB may maintain the RRM measurement configurationof the UE and may, (e.g, based on received measurement reports ortraffic conditions or bearer types), decide to ask a secondary gNB toprovide additional resources (serving cells) for a UE; upon receiving arequest from the master gNB, a secondary gNB may create a container thatmay result in the configuration of additional serving cells for the UE(or decide that it has no resource available to do so); for UEcapability coordination, the master gNB may provide (part of) the ASconfiguration and the UE capabilities to the secondary gNB; the mastergNB and the secondary gNB may exchange information about a UEconfiguration by employing of NR RRC containers (inter-node messages)carried in Xn messages; the secondary gNB may initiate a reconfigurationof its existing serving cells (e.g., PUCCH towards the secondary gNB);the secondary gNB may decide which cell is the PSCell within the SCG;the master gNB may or may not change the content of the NR RRCconfiguration provided by the secondary gNB; in the case of a SCGaddition and a SCG SCell addition, the master gNB may provide the latestmeasurement results for the SCG cell(s); both a master gNB and secondarygNBs may know the SFN and subframe offset of each other by OAM, (e.g.,for the purpose of DRX alignment and identification of a measurementgap). In an example, when adding a new SCG SCell, dedicated NR RRCsignaling may be used for sending required system information of thecell as for CA, except for the SFN acquired from a MIB of the PSCell ofa SCG.

In an example, serving cells may be grouped in a TA group (TAG). Servingcells in one TAG may use the same timing reference. For a given TAG,user equipment (UE) may use at least one downlink carrier as a timingreference. For a given TAG, a UE may synchronize uplink subframe andframe transmission timing of uplink carriers belonging to the same TAG.In an example, serving cells having an uplink to which the same TAapplies may correspond to serving cells hosted by the same receiver. AUE supporting multiple TAs may support two or more TA groups. One TAgroup may contain the PCell and may be called a primary TAG (pTAG). In amultiple TAG configuration, at least one TA group may not contain thePCell and may be called a secondary TAG (sTAG). In an example, carrierswithin the same TA group may use the same TA value and/or the sametiming reference. When DC is configured, cells belonging to a cell group(MCG or SCG) may be grouped into multiple TAGs including a pTAG and oneor more sTAGs.

FIG. 8 shows example TAG configurations as per an aspect of anembodiment of the present disclosure. In Example 1, pTAG comprisesPCell, and an sTAG comprises SCell1. In Example 2, a pTAG comprises aPCell and SCell1, and an sTAG comprises SCell2 and SCell3. In Example 3,pTAG comprises PCell and SCell1, and an sTAG1 includes SCell2 andSCell3, and sTAG2 comprises SCell4. Up to four TAGs may be supported ina cell group (MCG or SCG) and other example TAG configurations may alsobe provided. In various examples in this disclosure, example mechanismsare described for a pTAG and an sTAG. Some of the example mechanisms maybe applied to configurations with multiple sTAGs.

In an example, an eNB may initiate an RA procedure via a PDCCH order foran activated SCell. This PDCCH order may be sent on a scheduling cell ofthis SCell. When cross carrier scheduling is configured for a cell, thescheduling cell may be different than the cell that is employed forpreamble transmission, and the PDCCH order may include an SCell index.At least a non-contention based RA procedure may be supported forSCell(s) assigned to sTAG(s).

FIG. 9 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentdisclosure. An eNB transmits an activation command 600 to activate anSCell. A preamble 602 (Msg1) may be sent by a UE in response to a PDCCHorder 601 on an SCell belonging to an sTAG. In an example embodiment,preamble transmission for SCells may be controlled by the network usingPDCCH format 1A. Msg2 message 603 (RAR: random access response) inresponse to the preamble transmission on the SCell may be addressed toRA-RNTI in a PCell common search space (CSS). Uplink packets 604 may betransmitted on the SCell in which the preamble was transmitted.

According to some of the various aspects of embodiments, initial timingalignment may be achieved through a random access procedure. This mayinvolve a UE transmitting a random access preamble and an eNB respondingwith an initial TA command NTA (amount of timing advance) within arandom access response window. The start of the random access preamblemay be aligned with the start of a corresponding uplink subframe at theUE assuming NTA=0. The eNB may estimate the uplink timing from therandom access preamble transmitted by the UE. The TA command may bederived by the eNB based on the estimation of the difference between thedesired UL timing and the actual UL timing. The UE may determine theinitial uplink transmission timing relative to the correspondingdownlink of the sTAG on which the preamble is transmitted.

The mapping of a serving cell to a TAG may be configured by a servingeNB with RRC signaling. The mechanism for TAG configuration andreconfiguration may be based on RRC signaling. According to some of thevarious aspects of embodiments, when an eNB performs an SCell additionconfiguration, the related TAG configuration may be configured for theSCell. In an example embodiment, an eNB may modify the TAG configurationof an SCell by removing (releasing) the SCell and adding (configuring) anew SCell (with the same physical cell ID and frequency) with an updatedTAG ID. The new SCell with the updated TAG ID may initially be inactivesubsequent to being assigned the updated TAG ID. The eNB may activatethe updated new SCell and start scheduling packets on the activatedSCell. In an example implementation, it may not be possible to changethe TAG associated with an SCell, but rather, the SCell may need to beremoved and a new SCell may need to be added with another TAG. Forexample, if there is a need to move an SCell from an sTAG to a pTAG, atleast one RRC message, for example, at least one RRC reconfigurationmessage, may be send to the UE to reconfigure TAG configurations byreleasing the SCell and then configuring the SCell as a part of the pTAG(when an SCell is added/configured without a TAG index, the SCell may beexplicitly assigned to the pTAG). The PCell may not change its TA groupand may be a member of the pTAG.

The purpose of an RRC connection reconfiguration procedure may be tomodify an RRC connection, (e.g. to establish, modify and/or release RBs,to perform handover, to setup, modify, and/or release measurements, toadd, modify, and/or release SCells). If the received RRC ConnectionReconfiguration message includes the sCellToReleaseList, the UE mayperform an SCell release. If the received RRC Connection Reconfigurationmessage includes the sCellToAddModList, the UE may perform SCelladditions or modification.

In LTE Release-10 and Release-11 CA, a PUCCH is only transmitted on thePCell (PSCell) to an eNB. In LTE-Release 12 and earlier, a UE maytransmit PUCCH information on one cell (PCell or PSCell) to a given eNB.

As the number of CA capable UEs and also the number of aggregatedcarriers increase, the number of PUCCHs and also the PUCCH payload sizemay increase. Accommodating the PUCCH transmissions on the PCell maylead to a high PUCCH load on the PCell. A PUCCH on an SCell may beintroduced to offload the PUCCH resource from the PCell. More than onePUCCH may be configured for example, a PUCCH on a PCell and anotherPUCCH on an SCell. In the example embodiments, one, two or more cellsmay be configured with PUCCH resources for transmitting CSI/ACK/NACK toa base station. Cells may be grouped into multiple PUCCH groups, and oneor more cell within a group may be configured with a PUCCH. In anexample configuration, one SCell may belong to one PUCCH group. SCellswith a configured PUCCH transmitted to a base station may be called aPUCCH SCell, and a cell group with a common PUCCH resource transmittedto the same base station may be called a PUCCH group.

In an example embodiment, a MAC entity may have a configurable timertimeAlignmentTimer per TAG. The timeAlignmentTimer may be used tocontrol how long the MAC entity considers the Serving Cells belonging tothe associated TAG to be uplink time aligned. The MAC entity may, when aTiming Advance Command MAC control element is received, apply the TimingAdvance Command for the indicated TAG; start or restart thetimeAlignmentTimer associated with the indicated TAG. The MAC entitymay, when a Timing Advance Command is received in a Random AccessResponse message for a serving cell belonging to a TAG and/orif theRandom Access Preamble was not selected by the MAC entity, apply theTiming Advance Command for this TAG and start or restart thetimeAlignmentTimer associated with this TAG. Otherwise, if thetimeAlignmentTimer associated with this TAG is not running, the TimingAdvance Command for this TAG may be applied and the timeAlignmentTimerassociated with this TAG started. When the contention resolution isconsidered not successful, a timeAlignmentTimer associated with this TAGmay be stopped. Otherwise, the MAC entity may ignore the received TimingAdvance Command.

In example embodiments, a timer is running once it is started, until itis stopped or until it expires; otherwise it may not be running. A timercan be started if it is not running or restarted if it is running. Forexample, a timer may be started or restarted from its initial value.

Example embodiments of the disclosure may enable operation ofmulti-carrier communications. Other example embodiments may comprise anon-transitory tangible computer readable media comprising instructionsexecutable by one or more processors to cause operation of multi-carriercommunications. Yet other example embodiments may comprise an article ofmanufacture that comprises a non-transitory tangible computer readablemachine-accessible medium having instructions encoded thereon forenabling programmable hardware to cause a device (e.g. wirelesscommunicator, UE, base station, etc.) to enable operation ofmulti-carrier communications. The device may include processors, memory,interfaces, and/or the like. Other example embodiments may comprisecommunication networks comprising devices such as base stations,wireless devices (or user equipment: UE), servers, switches, antennas,and/or the like.

FIG. 11A, FIG. 11B, FIG. 11C, FIG. 11D, FIG. 11E, and FIG. 11F areexample diagrams for architectures of tight interworking between 5G RANand LTE RAN as per an aspect of an embodiment of the present disclosure.The tight interworking may enable a multiple RX/TX UE in RRC_CONNECTEDto be configured to utilize radio resources provided by two schedulerslocated in two base stations (e.g. (e)LTE eNB and gNB) connected via anon-ideal or ideal backhaul over the Xx interface between LTE eNB andgNB or the Xn interface between eLTE eNB and gNB. Base stations involvedin tight interworking for a certain UE may assume two different roles: abase station may either act as a master base station or as a secondarybase station. In tight interworking, a UE may be connected to one masterbase station and one secondary base station. Mechanisms implemented intight interworking may be extended to cover more than two base stations.

In FIG. 11A and FIG. 11B, a master base station may be an LTE eNB, whichmay be connected to EPC nodes (e.g. to an MME via the S1-C interface andto an S-GW via the S1-U interface), and a secondary base station may bea gNB, which may be a non-standalone node having a control planeconnection via an Xx-C interface to an LTE eNB. In the tightinterworking architecture of FIG. 11A, a user plane for a gNB may beconnected to an S-GW through an LTE eNB via an Xx-U interface betweenLTE eNB and gNB and an S1-U interface between LTE eNB and S-GW. In thearchitecture of FIG. 11B, a user plane for a gNB may be connecteddirectly to an S-GW via an S1-U interface between gNB and S-GW.

In FIG. 11C and FIG. 11D, a master base station may be a gNB, which maybe connected to NGC nodes (e.g. to a control plane core node via theNG-C interface and to a user plane core node via the NG-U interface),and a secondary base station may be an eLTE eNB, which may be anon-standalone node having a control plane connection via an Xn-Cinterface to a gNB. In the tight interworking architecture of FIG. 11C,a user plane for an eLTE eNB may be connected to a user plane core nodethrough a gNB via an Xn-U interface between eLTE eNB and gNB and an NG-Uinterface between gNB and user plane core node. In the architecture ofFIG. 11D, a user plane for an eLTE eNB may be connected directly to auser plane core node via an NG-U interface between eLTE eNB and userplane core node.

In FIG. 11E and FIG. 11F, a master base station may be an eLTE eNB,which may be connected to NGC nodes (e.g. to a control plane core nodevia the NG-C interface and to a user plane core node via the NG-Uinterface), and a secondary base station may be a gNB, which may be anon-standalone node having a control plane connection via an Xn-Cinterface to an eLTE eNB. In the tight interworking architecture of FIG.11E, a user plane for a gNB may be connected to a user plane core nodethrough an eLTE eNB via an Xn-U interface between eLTE eNB and gNB andan NG-U interface between eLTE eNB and user plane core node. In thearchitecture of FIG. 11F, a user plane for a gNB may be connecteddirectly to a user plane core node via an NG-U interface between gNB anduser plane core node.

FIG. 12A, FIG. 12B, and FIG. 12C are example diagrams for radio protocolstructures of tight interworking bearers as per an aspect of anembodiment of the present disclosure. In FIG. 12A, an LTE eNB may be amaster base station, and a gNB may be a secondary base station. In FIG.12B, a gNB may be a master base station, and an eLTE eNB may be asecondary base station. In FIG. 12C, an eLTE eNB may be a master basestation, and a gNB may be a secondary base station. In 5G network, theradio protocol architecture that a particular bearer uses may depend onhow the bearer is setup. Three example bearers including an MCG bearer,an SCG bearer, and a split bearer as shown in FIG. 12A, FIG. 12B, andFIG. 12C. NR RRC may be located in master base station, and SRBs may beconfigured as an MCG bearer type and may use the radio resources of themaster base station. Tight interworking may also be described as havingat least one bearer configured to use radio resources provided by thesecondary base station. Tight interworking may or may not beconfigured/implemented in example embodiments of the disclosure.

In the case of tight interworking, the UE may be configured with two MACentities: one MAC entity for master base station, and one MAC entity forsecondary base station. In tight interworking, the configured set ofserving cells for a UE may comprise of two subsets: the Master CellGroup (MCG) containing the serving cells of the master base station, andthe Secondary Cell Group (SCG) containing the serving cells of thesecondary base station. For a SCG, one or more of the following may beapplied: at least one cell in the SCG has a configured UL CC and one ofthem, named PSCell (or PCell of SCG, or sometimes called PCell), isconfigured with PUCCH resources; when the SCG is configured, there maybe at least one SCG bearer or one split bearer; upon detection of aphysical layer problem or a random access problem on a PSCell, or themaximum number of (NR) RLC retransmissions has been reached associatedwith the SCG, or upon detection of an access problem on a PSCell duringa SCG addition or a SCG change: a RRC connection re-establishmentprocedure may not be triggered, UL transmissions towards cells of theSCG are stopped, a master base station may be informed by the UE of aSCG failure type, for split bearer, the DL data transfer over the masterbase station is maintained; the RLC AM bearer may be configured for thesplit bearer; like PCell, PSCell may not be de-activated; PSCell may bechanged with a SCG change (e.g. with security key change and a RACHprocedure); and/or neither a direct bearer type change between a Splitbearer and a SCG bearer nor simultaneous configuration of a SCG and aSplit bearer are supported.

With respect to the interaction between a master base station and asecondary base station, one or more of the following principles may beapplied: the master base station may maintain the RRM measurementconfiguration of the UE and may, (e.g, based on received measurementreports, traffic conditions, or bearer types), decide to ask a secondarybase station to provide additional resources (serving cells) for a UE;upon receiving a request from the master base station, a secondary basestation may create a container that may result in the configuration ofadditional serving cells for the UE (or decide that it has no resourceavailable to do so); for UE capability coordination, the master basestation may provide (part of) the AS configuration and the UEcapabilities to the secondary base station; the master base station andthe secondary base station may exchange information about a UEconfiguration by employing of RRC containers (inter-node messages)carried in Xn or Xx messages; the secondary base station may initiate areconfiguration of its existing serving cells (e.g., PUCCH towards thesecondary base station); the secondary base station may decide whichcell is the PSCell within the SCG; the master base station may notchange the content of the RRC configuration provided by the secondarybase station; in the case of a SCG addition and a SCG SCell addition,the master base station may provide the latest measurement results forthe SCG cell(s); both a master base station and a secondary base stationmay know the SFN and subframe offset of each other by OAM, (e.g., forthe purpose of DRX alignment and identification of a measurement gap).In an example, when adding a new SCG SCell, dedicated RRC signaling maybe used for sending required system information of the cell as for CA,except for the SFN acquired from a MIB of the PSCell of a SCG.

FIG. 13A and FIG. 13B are example diagrams for gNB deployment scenariosas per an aspect of an embodiment of the present disclosure. In thenon-centralized deployment scenario in FIG. 13A, the full protocol stack(e.g. NR RRC, NR PDCP, NR RLC, NR MAC, and NR PHY) may be supported atone node. In the centralized deployment scenario in FIG. 13B, upperlayers of gNB may be located in a Central Unit (CU), and lower layers ofgNB may be located in Distributed Units (DU). The CU-DU interface (e.g.Fs interface) connecting CU and DU may be ideal or non-ideal. Fs-C mayprovide a control plane connection over Fs interface, and Fs-U mayprovide a user plane connection over Fs interface. In the centralizeddeployment, different functional split options between CU and DUs may bepossible by locating different protocol layers (RAN functions) in CU andDU. The functional split may support flexibility to move RAN functionsbetween CU and DU depending on service requirements and/or networkenvironments. The functional split option may change during operationafter Fs interface setup procedure, or may change only in Fs setupprocedure (i.e. static during operation after Fs setup procedure).

FIG. 14 is an example diagram for different functional split optionexamples of the centralized gNB deployment scenario as per an aspect ofan embodiment of the present disclosure. In the split option example 1,an NR RRC may be in CU, and NR PDCP, NR RLC, NR MAC, NR PHY, and RF maybe in DU. In the split option example 2, an NR RRC and NR PDCP may be inCU, and NR RLC, NR MAC, NR PHY, and RF may be in DU. In the split optionexample 3, an NR RRC, NR PDCP, and partial function of NR RLC may be inCU, and the other partial function of NR RLC, NR MAC, NR PHY, and RF maybe in DU. In the split option example 4, an NR RRC, NR PDCP, and NR RLCmay be in CU, and NR MAC, NR PHY, and RF may be in DU. In the splitoption example 5, an NR RRC, NR PDCP, NR RLC, and partial function of NRMAC may be in CU, and the other partial function of NR MAC, NR PHY, andRF may be in DU. In the split option example 6, an NR RRC, NR PDCP, NRRLC, and NR MAC may be in CU, and NR PHY and RF may be in DU. In thesplit option example 7, an NR RRC, NR PDCP, NR RLC, NR MAC, and partialfunction of NR PHY may be in CU, and the other partial function of NRPHY and RF may be in DU. In the split option example 8, an NR RRC, NRPDCP, NR RLC, NR MAC, and NR PHY may be in CU, and RF may be in DU.

The functional split may be configured per CU, per DU, per UE, perbearer, per slice, or with other granularities. In per CU split, a CUmay have a fixed split, and DUs may be configured to match the splitoption of CU. In per DU split, a DU may be configured with a differentsplit, and a CU may provide different split options for different DUs.In per UE split, a gNB (CU and DU) may provide different split optionsfor different UEs. In per bearer split, different split options may beutilized for different bearer types. In per slice splice, differentsplit options may be applied for different slices.

In an example embodiment, the new radio access network (new RAN) maysupport different network slices, which may allow differentiatedtreatment customized to support different service requirements with endto end scope. The new RAN may provide a differentiated handling oftraffic for different network slices that may be pre-configured, and mayallow a single RAN node to support multiple slices. The new RAN maysupport selection of a RAN part for a given network slice, by one ormore slice ID(s) or NSSAI(s) provided by a UE or a NGC (e.g. NG CP). Theslice ID(s) or NSSAI(s) may identify one or more of pre-configurednetwork slices in a PLMN. For initial attach, a UE may provide a sliceID and/or an NSSAI, and a RAN node (e.g. gNB) may use the slice ID orthe NSSAI for routing an initial NAS signaling to an NGC control planefunction (e.g. NG CP). If a UE does not provide any slice ID or NSSAI, aRAN node may send a NAS signaling to a default NGC control planefunction. For subsequent accesses, the UE may provide a temporary ID fora slice identification, which may be assigned by the NGC control planefunction, to enable a RAN node to route the NAS message to a relevantNGC control plane function. The new RAN may support resource isolationbetween slices. The RAN resource isolation may be achieved by avoidingthat shortage of shared resources in one slice breaks a service levelagreement for another slice.

The amount of data traffic carried over cellular networks is expected toincrease for many years to come. The number of users/devices isincreasing and a user/device accesses an increasing number and varietyof services, e.g. video delivery, large files, images. This requiresprovisioning a high data rates and capacity in the network to meetcustomers' expectations. More spectrum is therefore needed for cellularoperators to meet the increasing demand. Considering user expectationsof high data rates along with seamless mobility, it is beneficial thatmore spectrum be made available for deploying macro cells as well assmall cells for cellular systems.

Striving to meet the market demands, there has been increasing interestfrom operators in deploying some complementary access utilizingunlicensed spectrum to meet the traffic growth. This is exemplified bythe large number of operator-deployed Wi-Fi networks and the 3GPPstandardization of LTE/WLAN interworking solutions. This interestindicates that unlicensed spectrum, when present, can be an effectivecomplement to licensed spectrum for cellular operators to helpaddressing the traffic explosion in some scenarios, such as hotspotareas. LAA offers an option for operators to make use of unlicensedspectrum while managing one radio network, thus offering newpossibilities for optimizing the network's efficiency.

In an example embodiment, Listen-before-talk (clear channel assessment)may be implemented for transmission in an LAA cell. In alisten-before-talk (LBT) procedure, equipment may apply a clear channelassessment (CCA) check before using the channel. For example, the CCAutilizes at least energy detection to determine the presence or absenceof other signals on a channel in order to determine if a channel isoccupied or clear, respectively. For example, European and Japaneseregulations mandate the usage of LBT in the unlicensed bands. Apart fromregulatory requirements, carrier sensing via LBT may be one way for fairsharing of the unlicensed spectrum.

In an example embodiment, discontinuous transmission on an unlicensedcarrier with limited maximum transmission duration may be enabled. Someof these functions may be supported by one or more signals to betransmitted from the beginning of a discontinuous LAA downlinktransmission. Channel reservation may be enabled by the transmission ofsignals, by an LAA node, after gaining channel access via a successfulLBT operation, so that other nodes that receive the transmitted signalwith energy above a certain threshold sense the channel to be occupied.Functions that may need to be supported by one or more signals for LAAoperation with discontinuous downlink transmission may include one ormore of the following: detection of the LAA downlink transmission(including cell identification) by UEs; time & frequency synchronizationof UEs.

In an example embodiment, DL LAA design may employ subframe boundaryalignment according to LTE-A carrier aggregation timing relationshipsacross serving cells aggregated by CA. This may not imply that the eNBtransmissions can start only at the subframe boundary. LAA may supporttransmitting PDSCH when not all OFDM symbols are available fortransmission in a subframe according to LBT. Delivery of controlinformation for the PDSCH may be supported.

LBT procedure may be employed for fair and friendly coexistence of LAAwith other operators and technologies operating in unlicensed spectrum.LBT procedures on a node attempting to transmit on a carrier inunlicensed spectrum require the node to perform a clear channelassessment to determine if the channel is free for use. An LBT proceduremay involve at least energy detection to determine if the channel isbeing used. For example, regulatory requirements in some regions, e.g.,in Europe, specify an energy detection threshold such that if a nodereceives energy greater than this threshold, the node assumes that thechannel is not free. While nodes may follow such regulatoryrequirements, a node may optionally use a lower threshold for energydetection than that specified by regulatory requirements. In an example,LAA may employ a mechanism to adaptively change the energy detectionthreshold, e.g., LAA may employ a mechanism to adaptively lower theenergy detection threshold from an upper bound. Adaptation mechanism maynot preclude static or semi-static setting of the threshold. In anexample Category 4 LBT mechanism or other type of LBT mechanisms may beimplemented.

Various example LBT mechanisms may be implemented. In an example, forsome signals, in some implementation scenarios, in some situations,and/or in some frequencies no LBT procedure may performed by thetransmitting entity. In an example, Category 2 (e.g. LBT without randomback-off) may be implemented. The duration of time that the channel issensed to be idle before the transmitting entity transmits may bedeterministic. In an example, Category 3 (e.g. LBT with random back-offwith a contention window of fixed size) may be implemented. The LBTprocedure may have the following procedure as one of its components. Thetransmitting entity may draw a random number N within a contentionwindow. The size of the contention window may be specified by theminimum and maximum value of N. The size of the contention window may befixed. The random number N may be employed in the LBT procedure todetermine the duration of time that the channel is sensed to be idlebefore the transmitting entity transmits on the channel. In an example,Category 4 (e.g. LBT with random back-off with a contention window ofvariable size) may be implemented. The transmitting entity may draw arandom number N within a contention window. The size of contentionwindow may be specified by the minimum and maximum value of N. Thetransmitting entity may vary the size of the contention window whendrawing the random number N. The random number N is used in the LBTprocedure to determine the duration of time that the channel is sensedto be idle before the transmitting entity transmits on the channel.

LAA may employ uplink LBT at the UE. The UL LBT scheme may be differentfrom the DL LBT scheme (e.g. by using different LBT mechanisms orparameters) for example, since the LAA UL is based on scheduled accesswhich affects a UE's channel contention opportunities. Otherconsiderations motivating a different UL LBT scheme include, but are notlimited to, multiplexing of multiple UEs in a single subframe.

In an example, a DL transmission burst may be a continuous transmissionfrom a DL transmitting node with no transmission immediately before orafter from the same node on the same CC. An UL transmission burst from aUE perspective may be a continuous transmission from a UE with notransmission immediately before or after from the same UE on the sameCC. In an example, UL transmission burst is defined from a UEperspective. In an example, an UL transmission burst may be defined froman eNB perspective. In an example, in case of an eNB operating DL+UL LAAover the same unlicensed carrier, DL transmission burst(s) and ULtransmission burst(s) on LAA may be scheduled in a TDM manner over thesame unlicensed carrier. For example, an instant in time may be part ofa DL transmission burst or an UL transmission burst.

A NR (New Radio) may support a multi-beam operation. In an example, agNB, a bae station in the NR, operating on a high frequency band maybroadcast one or more NR synchronization signal (SS) using differenttransmitting beams in different radio resources in time and frequency.

An SS may be based on Cyclic Prefix-Orthogonal Frequency DivisionMultiplexing (CP-OFDM). The SS may comprise at least two types ofsynchronization signals; NR-PSS (Primary synchronization signal) andNR-SSS (Secondary synchronization signal). NR-PSS may be defined atleast for initial symbol boundary synchronization to the NR cell. NR-SSSmay be defined for detection of NR cell ID or at least part of NR cellID. NR-SSS detection may be based on the fixed time/frequencyrelationship with NR-PSS resource position irrespective of duplex modeand beam operation type at least within a given frequency range and CPoverhead. Normal CP may be supported for NR-PSS and NR-SSS.

The NR may comprise at least one physical broadcast channel (NR-PBCH).When a gNB transmit (or broadcast) the NR-PBCH, a UE may decode theNR-PBCH based on the fixed relationship with NR-PSS and/or NR-SSSresource position irrespective of duplex mode and beam operation type atleast within a given frequency range and CP overhead. NR-PBCH may be anon-scheduled broadcast channel carrying at least a part of minimumsystem information with fixed payload size and periodicity predefined inthe specification depending on carrier frequency range.

In single beam and multi-beam scenarios, NR may comprise an SS blockthat may support time (frequency, and/or spatial) division multiplexingof NR-PSS, NR-SSS, and NR-PBCH. A gNB may transmit NR-PSS, NR-SSS and/orNR-PBCH within an SS block. For a given frequency band, an SS block maycorrespond to N OFDM symbols based on the default subcarrier spacing,and N may be a constant. The signal multiplexing structure may be fixedin NR. A UE may identify at least OFDM symbol index, slot index in aradio frame and radio frame number from an SS block.

A NR may support an SS burst comprising one or more SS blocks. An SSburst set may comprise one or more SS bursts. For example, a number ofSS bursts within a SS burst set may be finite. From physical layerspecification perspective, NR may support at least one periodicity of SSburst set. From UE perspective, SS burst set transmission may beperiodic, and UE may assume that a given SS block is repeated with an SSburst set periodicity.

Within an SS burset set periodicity, NR-PBCH repeated in one or more SSblocks may change. A set of possible SS block time locations may bespecified per frequency band in an RRC message. The maximum number ofSS-blocks within SS burst set may be carrier frequency dependent. Theposition(s) of actual transmitted SS-blocks may be informed at least forhelping CONNECTED/IDLE mode measurement, for helping CONNECTED mode UEto receive downlink (DL) data/control in one or more SS-blocks, or forhelping IDLE mode UE to receive DL data/control in one or moreSS-blocks. A UE may not assume that the gNB transmits the same number ofphysical beam(s). A UE may not assume the same physical beam(s) acrossdifferent SS-blocks within an SS burst set. For an initial cellselection, UE may assume default SS burst set periodicity which may bebroadcast via an RRC message and frequency band-dependent. At least formulti-beams operation case, the time index of SS-block may be indicatedto the UE.

For CONNECTED and IDLE mode UEs, NR may support network indication of SSburst set periodicity and information to derive measurementtiming/duration (e.g., time window for NR-SS detection). A gNB mayprovide (e.g., via broadcasting an RRC message) one SS burst setperiodicity information per frequency carrier to UE and information toderive measurement timing/duration if possible. In case that one SSburst set periodicity and one information regarding timing/duration areindicated, UE may assume the periodicity and timing/duration for allcells on the same carrier. If a gNB does not provide indication of SSburst set periodicity and information to derive measurementtiming/duration, a UE may assume a predefined periodicity, e.g., 5 ms,as the SS burst set periodicity. NR may support set of SS burst setperiodicity values for adaptation and network indication.

For initial access, UE may assume a signal corresponding to a specificsubcarrier spacing of NR-PSS/SSS in a given frequency band given by a NRspecification. For NR-PSS, a Zadoff-Chu (ZC) sequence may be employed asa sequence for NR-PSS. NR may define at least one basic sequence lengthfor a SS in case of sequence-based SS design. The number of antenna portof NR-PSS may be 1. For NR-PBCH transmission, NR may support a fixednumber of antenna port(s). A UE may not require a blind detection ofNR-PBCH transmission scheme or number of antenna ports. A UE may assumethe same PBCH numerology as that of NR-SS. For the minimum systeminformation delivery, NR-PBCH may comprise a part of minimum systeminformation. NR-PBCH contents may comprise at least a part of the SFN(system frame number) or CRC. A gNB may transmit the remaining minimumsystem information in shared downlink channel via NR-PDSCH.

A NR may support contention-based random access (CBRA) andcontention-free random access (CFRA) procedures. The CBRA may comprise afour-step random access (RA) procedure which may comprise: RA preamble(RAP) transmission from a user equipment (UE) to a base station in NR,referred to as gNB, random access response (RAR) transmission from thegNB to the UE, scheduled transmission of one or more transport blocks(TBs) from the UE to the gNB, and contention resolution as illustratedin FIG. 15(a). The CFRA may comprise the first two steps of CBRA, whichmay comprise the RAP transmission by a UE and RAR transmission by a gNB.In the CFRA, gNB may assign a dedicated RAP to a UE via one or moreradio resource control (RRC) messages or via a downlink control channel,e.g., PDCCH, EPDCCH, or MPDCCH, in the form of downlink controlinformation (DCI), e.g., DCI format 1A, 6-1A, or 6-1B in LTE. Thededicated RAP may result in completing a CFRA at the second step of CBRAby skipping a contention resolution as illustrated in FIG. 15(b).

For the RAP transmission, gNB may transmit one or more radio resourcecontrol (RRC) messages and/or one or more control messages, e.g.,downlink control information (DCI) via PDCCH, for indicating a randomaccess channel (RACH) configuration which may comprise at least one ormore physical random access channel (PRACH) resources for transmitting aRAP, a RAP format, or RACH sequence information for generating a RAP fortransmitting to the gNB.

For CBRA, a gNB may broadcast RACH configurations, e.g.,rach-ConfigCommon and prach-Config broadcast via as a part of systeminformation block, possibly per beam via NR-PBCH. The UE may randomlydetermine a RAP from RACH sequences generated based on the RACHconfiguration and may transmit the determined RAP via one or more RACHradio resources configured by the RACH configuration.

In CBRA, the random selection of RAP from the RACH sequences may resultin the case that multiple UEs may transmit the same RAP via the sameRACH radio resource(s). A gNB that may receive the same RAP from themultiple UEs may or may not detect the RAP. In the CBRA, the contentionresolution resulted from the same RAP transmission by multiple UEs maybe resolved in the last step of CBRA.

A UE may be configured with CFRA, for example, for handover to a newcell or for adding a secondary cell. For CFRA, the UE may receive theRACH configuration from one or more dedicated message transmitted by agNB. In an example, for handover, a target base station may transmit, toa source base station, a RACH configuration for a UE. The source basestation may transmit an RRC message comprising the RACH configuration toa UE. The RACH configuration may indicate a handover to the target basestation with the RACH configuration. For adding a secondary cell, a UEmay receive, from a base station, the RACH configuration via a downlinkcontrol channel, e.g., PDCCH, EPDCCH, or MPDCCH, in the form of DCI,and/or an RRC message.

For CFRA, the preamble to transmit by a UE may be explicitly indicatedby a gNB. In an example, for handover, one or more RRC messagestransmitted by a gNB for CFRA may comprise a dedicated RACHconfiguration for CFRA, e.g., RACH-ConfigDedicated in LTE. The dedicatedRACH configuration may comprise at least a dedicated preamble index,e.g., ra-Preamblelndex, and/or RACH configuration index, e.g.,ra-PRACH-Masklndex.

In an example, for adding a secondary cell, one or more control messagestransmitted by a gNB via a physical layer control channel may bescrambled by a cell radio network temporary identifier (C-RNTI) assignedto a UE. The one or more control messages may comprise at least acarrier indicator, e.g., 0 or 3 bits assigned for indicating a carrierin DCI format 1A in LTE, a preamble index, e.g., 6 bits assigned forindicating Preamble index in DCI format 1A in LTE, or RACH configurationindex, e.g., 4 bits assigned for indicating PRACH Mask Index in DCIformat 1A in LTE.

For the case of CFRA, a preamble may be dedicated for a UE to preventmultiple UEs from transmitting the same RAP. A gNB may select a RAP forCFRA from sequences outside one or more RAP sequence sets used for CBRAand/or may select a RAP for CFRA from one or more reserved sequences inone or more RAP sequences used for CBRA and CFRA.

A gNB may transmit a medium access control (MAC) packet data unit (PDU)comprising one or more RA responses (RARs) to the UE in response toreception of a RAP that a UE transmits. A UE may monitor thephysical-layer downlink control channel (PDCCH) for RARs identified by arandom access RNTI (RA-RNTI) in a RA response window which may starts atthe subframe, slot, or mini-slot that comprises the end of a RAPtransmission plus a time offset, e.g., three subframes or zerosubframes. The size of the RA response window may be configurable, e.g.,ra-ResponseWindowSize.

A gNB may transmit a response corresponding to the UE's RAPtransmission. The response may be scrambled with the RA-RNTI. A UE mayidentify, based on the RA-RNTI, whether an RAR received from a gNB isfor the UE or not. The RA-RNTI may be determined at least based on atime and frequency radio resource where a UE transmits a RAP, which mayresult in a plurality of UEs having the same RA-RNTI. For example, inLTE, a UE may compute the RA-RNTI associated with the PRACH in which theUE transmits a RAP as:

RA-RNTI=1+t_id+10*f_id

where t_id is the index of the first subframe of the specified PRACH(0≤t_id<10), and f_id is the index of the specified PRACH within thatsubframe, in ascending order of frequency domain (0≤f_id<6) except forNB-IoT UEs, BL UEs or UEs in enhanced coverage. NB-IoT, BL-UE, and/or aUE in enhanced coverage may employ different formulas for RA-RNTIcalculations. In NR, the RA-RNTI may comprise at least an subframe indexof a specified PRACH (time occasion) and a frequency index of thespecified PRACH within the subframe. In an example, for BL UEs and UEsin enhanced coverage, RA-RNTI associated with the PRACH in which theRandom Access Preamble is transmitted, may be computed as:

RA-RNTI=1+t_id+10*f_id+60*(SFN_id mod(Wmax/10))

where t_id is the index of the first subframe of the specified PRACH(0≤t_id<10), f_id is the index of the specified PRACH within thatsubframe, in ascending order of frequency domain (0≤f_id<6), SFN_id isthe index of the first radio frame of the specified PRACH, and Wmax is400, maximum possible RAR window size in subframes for BL UEs or UEs inenhanced coverage. For NB-IoT UEs, the RA-RNTI associated with the PRACHin which the Random Access Preamble is transmitted, may be computed as:

RA-RNTI=1+floor(SFN_id/4)

where SFN_id is the index of the first radio frame of the specifiedPRACH.

In response to transmitting a RAP, a UE may start to monitor PDCCH forat least one RAR detection. A UE may stop monitoring for RAR(s) afterdecoding of a MAC PDU for a RAR comprising a RAP identifier (RAPID) thatmatches the RAP transmitted by the UE. The MAC PDU may comprise one ormore MAC RARs and a MAC header that may comprise a subheader having abackoff indicator (BI) and one or more subheaders that comprise RAPIDs.FIG. 16 illustrates an example of a MAC PDU comprising a MAC header andMAC RARs. If a RAR comprises a RAPID corresponding to the RAP that a UEtransmits, the UE may employ one or more parameters in the RAR, e.g., atiming advance (TA) command, a UL grant, and a Temporary C-RNTI(TC-RNTI) in LTE, to a subsequent transmission. FIG. 17 illustratesexamples of MAC RAR comprising a TA command, a UL grant, and a TC-RNTI.

For CFRA, a UE may receive an RAR comprising an RAP dedicated(preassigned) to the UE that is different from RAPs assigned to otherUEs. In this case, in response to receiving an RAR comprising a RAPIDcorresponding to the transmitted RAP, a UE may complete the CFRAprocedure. There may be no need to handle contention for CFRA since theUE may have a RAP assigned by a gNB.

For CBRA, if a UE receives an RAR comprising an RAPID corresponding tothe UE's transmitted RAP, the UE may adjust UL time alignment byemploying the TA value corresponding to the TA command in the receivedRAR and may transmit one or more TBs to a gNB employing the UL resourcesindicated by the UL grant in the received RAR. The TBs that a UEtransmits may comprise RRC signaling, such as RRC connection request,RRC connection Re-establishment request, or RRC connection resumerequest, and a UE identity (e.g., TC-RNTI), as the identity is used aspart of the contention-resolution mechanism in the last step of theCBRA.

The last step of the CBRA procedure may comprise a DL messagetransmitted by a gNB for contention resolution. For the case of the sameRAP transmissions by multiple UEs, the multiple UEs may receive the sameRAR with the same TC-RNTI in the second step of CBRA. The contentionresolution in the last step may be to ensure that a UE does notincorrectly use another UE Identity. The contention resolution mechanismmay be based on either C-RNTI on PDCCH or Contention Resolution Identityon DL-SCH depending on whether a UE has a C-RNTI or not. If a UE hasC-RNTI, upon detection of C-RNTI on the PDCCH, the UE may determine thesuccess of RA procedure. If a UE does not have C-RNTI pre-assigned, theUE may monitor DL-SCH associated with TC-RNTI that a gNB transmits in aRAR of the second step and may compare the identity in the datatransmitted by the gNB on DL-SCH with the identity that the UEtransmits. If the two identities are identical, the UE may determine thesuccess of RA procedure and promote the TC-RNTI to the C-RNTI.

The last step in the RA procedure may allow Hybrid automatic repeatrequest (HARQ) retransmission. A UE may startmac-ContentionResolutionTimer when the UE transmits one or more TB s toa gNB in the third step and may restart mac-ContentionResolutionTimer ata HARQ retransmission. When a UE receives data on the DL resourcesidentified by C-RNTI or TC-RNTI in the last step, the UE may stop themac-ContentionResolutionTimer. If the UE does not detect the contentionresolution identity that matches to the identity transmitted by the UEin the third step, the UE may determine the failure of RA procedure anddiscard the TC-RNTI. If mac-ContentionResolutionTimer expires, the UEmay determine the failure of RA procedure and discard the TC-RNTI. Ifthe contention resolution is failed, a UE may flush the HARQ buffer usedfor transmission of the MAC PDU and may restart the four-step RAprocedure from the first step. The UE may delay the subsequent RAPtransmission by the backoff time randomly selected according to auniform distribution between 0 and the backoff parameter valuecorresponding the BI in the MAC PDU for RAR.

In the RA procedure, the usage of the first two steps may be to obtainUL time alignment and an UL grant for a UE. The UL time alignment maynot be necessary in one or more scenarios. For example, in small cellsor for stationary wireless devices, the process for acquiring the ULtime alignment may not be necessary if a TA value is zero (e.g., smallcells) or a stored TA value from the last TAC (in RAR and/or in MAC CE)may serve for the current RA (stationary wireless device). For the casethat a UE may be in RRC connected with a valid TA value and no resourceconfigured for UL transmission, the UL time alignment may not benecessary when the UE needs to obtain an UL grant.

In a multi-beam operation, gNB may perform a downlink beam sweep toprovide coverage for DL synchronization signals (SSs) and common controlchannels. To enable UEs to access the cell, the UEs may perform thesimilar sweep for UL direction.

In the single beam scenarios, a gNB may configure time-repetition withinone SS block in a wide beam. In multi-beam scenarios, a gNB mayconfigure one or more SS blocks with multiple transmitting (Tx) beamssuch that a UE identifies at least one of OFDM symbol index, slot indexin a radio frame, or radio frame number from an SS block.

In NR with multi-beam operation, the SS block may comprise anassociation between SS blocks and a subset of RACH resources and/or asubset of RAP indices. UE may determine a subset of RACH resourcesand/or a subset of RAP indices based on DL measurements on SS blocks.

In the multi-beam scenario, a gNB may repeat a transmission ofPSS/SSS/PBCH using different Tx beams, e.g., Tx beam sweeping, toprovide a DL coverage for supporting cell selection/reselection andinitial access procedures. NR may support a SS comprising a tertiarysynchronization signal (TSS). The TSS may be employed for indicating oneor more differences in the repeated PRACH configurations via one or morebeams within an SS Burst. Under the assumption that PBCH carries thePRACH configuration, a gNB may broadcast PRACH configurations possiblyper beam with the TSS. FIG. 18 is an example of the RA procedure, wherea gNB broadcast multiple SS blocks.

In NR, a gNB may configure an association between DL signal/channel of aSS block, and a subset of RACH resources and/or a subset of preambleindices, for determining a DL Tx beam for transmitting a RAR. In anexample, for multiple SS blocks broadcast by a gNB, a UE may measure DLsignal/channel of the multiple SS blocks and select one of configuredPRACH radio resources associated with one of the multiple SS blocks. Theselected PRACH radio resource may be associated with an SS blockproviding a received signal strength higher than a predefined thresholdat the UE. Transmitting a RAP over one of configured PRACH radioresources may indicate a UE's preferred DL Tx beam to a gNB. If the gNBdetect the RAP, an RAR corresponding to the RAP may be transmitted usingthe DL Tx beam that the UE prefers.

In a multi-beam system, a gNB may configure different types of PRACHresources associated with SS blocks and/or DL beams. In NR, a PRACHtransmission occasion may be defined as the time-frequency radioresource on which a UE transmits a preamble using the configured PRACHpreamble format with a UE Tx beam and for which gNB performs PRACHpreamble detection. One PRACH occasion may be used to cover the Tx/Rxbeam non-correspondence case at TRP (transmission and reception point)and/or UE. gNB may perform RX sweep during PRACH occasion as UE TX beamalignment is fixed during single occasion. A PRACH burst may mean a setof PRACH occasions allocated consecutively in time domain, and a PRACHburst set may mean a set of PRACH bursts to enable full RX sweep. FIG.19 illustrates an example of configured PRACH occasion, PRACH burst, andPRACH burst set.

There may be an association between SS blocks (DL signal/channel) andPRACH occasion and a subset of PRACH preamble resources. One PRACHoccasion may comprise a set of preambles. In multi beam operation, thegNB may need to know which beam or set of beams it may use to transmitan RAR and the preambles may be used to indicate that.

The timing from SS block to the PRACH resource may be indicated in theMIB. In an example, different TSS may be used for different timings suchthat the detected sequence within TSS indicates the PRACH resource. ThisPRACH configuration may be specified as a timing relative to the SSblock, and may be given as a combination of the payload in the MIB andanother broadcast system information.

Association between SS block and a subset of RACH resources and/or asubset of preamble indices may be configured so that TRP may identify aDL beam (preferred DL beam) for a UE according to resource location orpreamble index of received preamble. An association may be independentand at least either a subset of RACH resources or subset of preambleindices may not be allowed to be associated with multiple SS blocks.

PRACH resources may be partitioned on SS-blocks basis in the multiplebeam operation. There may be one to one and/or many to one mappingbetween SS-blocks and PRACH occasions. FIG. 20 illustrates an example ofTDD (FIG. 20(a)) and FDD (FIG. 20(b)) based one to one mapping andmulti-to-one mapping (FIG. 20(c)) between SS-blocks and PRACH occasions.

UE may detect SS-block based on DL synchronization signals anddifferentiate SS-blocks based on the time index. With one-to-one mappingof beam or beams used to transmit SS-block and a specific PRACHoccasion, the transmission of PRACH preamble resource may be anindication informed by a UE to gNB of the preferred SS-block (that mayindicate the preferred DL Tx beam employed to transmit the preferredSS-block). This way the PRACH preamble resources of single PRACHoccasion may correspond to specific SS-block and mapping may be donebased on the SS-block index. There may be one to one mapping between anSS-block beam and a PRACH occasion. There may not be such mapping forthe SS-block periodicity and RACH occasion periodicity.

Depending on the gNB capability (e.g. the used beamforming architecture,analog/hybrid/digital beamforming), there may not be one to one mappingbetween a SS-block and a RACH occasion. In case beam or beams used fortransmitting SS-block and receiving during RACH occasion do notcorrespond directly, e.g., gNB may form receive beams that covermultiple SS-blocks beams, the preambles of PRACH occasion may be dividedbetween the different SS-blocks in a manner that a subset of PRACHpreambles map to specific SS-block.

In the multi-beam RACH scenario, based on the mapping between DL beamstransmitting SS blocks and PRACH resources, e.g. time/frequency slot andpossibly preamble partitioning, a UE may be under the coverage of agiven DL beam or at least a subset of them in a cell. That may enable agNB to transmit an RAR in this DL beam and/or perform a beam sweepingprocedure e.g. not transmitting the same RAR message in possible beams(e.g. transmitting the RAR in a single beam as in the figure below) asillustrated in FIG. 21. A gNB may broadcast one or more systeminformation comprising the mapping periodically, e.g., for a RRC idleUE, or may transmit one or more UE-specific RRC messages comprising themapping based upon a request, e.g., for a RRC connected UE.

With beam-specific PRACH resources, a gNB DL TX beam may be associatedwith a subset of preambles. The beam specific PRACH preambles resourcesmay be associated with DL Tx beams that are identified by periodicalbeam and/or CSI-RS, e.g., CSI-RS for L3 Mobility (same signals may beused for L2 beam management/intra-cell mobility as well). A UE maydetect the beams without RRC configuration, e.g., reading the beamconfiguration from minimum SI (MIB/SIB).

In an example, a gNB may transmit to a UE one or more messagescomprising configuration parameters of one or more cells. Theconfiguration parameters may comprise parameters of a plurality ofCSI-RS signal format and/or resources. The configuration parameters maycomprise one or more parameters for indicating at least one of CSI-RSperiodicity, CSI-RS subcarriers (e.g. resource elements), or CSI-RSsequence. Based on the configuration parameters of CSI-RS, a UE maydetermine when to (e.g., time) and/or where (e.g., frequency) to measurea pathloss (or perform a radio link measurement) of the configuredCSI-RS.

The PRACH resource mapping to specific beams may use SS-blockassociation. Specific beams may be associated with the beams used fortransmitting SS-block as illustrated in FIG. 22. In FIG. 22(a), gNB maytransmit SS-block using one or multiple beams (in case ofanalogue/hybrid beamforming), but individual beams may not be detected.From the UE perspective, this may be a single beam transmission. In FIG.22(b), gNB may transmit CSI-RS (for Mobility) using individual beamsassociated with specific SS-block. A UE may detect individual beamsbased on the CSI-RS.

In an example, a gNB may transmit to a UE the one or more messagescomprising one or more parameters for indicating the correspondencebetween SS blocks and CSI-RS signals. The one or more messages may beRRC connection setup message, RRC connection resume message, and/or RRCconnection reconfiguration message.

In an example, a UE in RRC-Idle mode may not be configured with CSI-RSsignals and may receive SS blocks. A UE not configured with CSI-RS maymeasure a pathloss based on SS signals. A UE in RRC-connected mode, maybe configured with CSI-RS signals and may be measure pathloss based onCSI-RS signals. In an example, a UE in RRC inactive mode may measure thepathloss based on SS blocks, e.g. when the UE moves to a different gNBthat has a different CSI-RS configuration compared with the serving gNB.

For a handover case, a UE may be configured to measure one or more SSblocks and/or CSI-RSs in a neighboring cell. If at least one of theneighboring cell SS-block measurements triggers a handover request, asource gNB may transmit one or more parameters for indicating at leastone preferred beam in a handover request to a target gNB based on themeasurements. In response to receiving the at least one preferred beam,the target gNB may transmit at least one beam-specific dedicated RACHresource and/or at least one RAP in the handover command. In an example,the target gNB may provide a set of dedicated resources e.g. one for atleast one SS-block in the handover command. The UE may transmit the atleast one RAP corresponding to the preferred DL beam in the target cell.

PRACH occasion may be mapped to corresponding SS-block, and a set ofPRACH preambles may be divided between beams as illustrated in FIG.23(a). Similar to mapping of multiple SS-blocks to single PRACHoccasion, multiple beams of an SS-block may be mapped to at least onePRACH occasion as illustrated in FIG. 23(b).

If a PRACH occasion is configured with k preambles, and a PRACH occasionis configured to be SS-block specific, the k preambles may be used toindicate the specific SS-block. In this case, there may be N PRACHoccasions corresponding to N SS-blocks. If multiple SS-blocks are mappedto single PRACH occasion, then the preambles may be divided betweenSS-blocks and depending on the number of SS-blocks, the availablepreambles per SS-block may be K/N (K preambles, N SS-blocks). If KSS-block specific preambles are divided between CSI-RS beams in thecorresponding PRACH occasions, the number of available preambles perbeam may be determined by the K preambles/number of beams. If thepreambles are partitioned in SS-block specific manner, the UE mayindicate preferred SS-block but not the preferred individual DL TX beamto gNB.

The network may configure mapping/partitioning PRACH preamble resourcesto SS-blocks and/or to individual beams. A UE may determine the usedpartitioning of PRACH preambles, as much as possible, e.g. based on thePRACH configuration.

Beam-specific PRACH configurations may be configurable when a gNB usesanalog RX beamforming. In that case, when a UE transmits, for example, apreamble in a beam-specific time/frequency slot associated with one ormultiple SS Block transmissions, then the gNB may use the appropriate RXbeamforming when receiving the preamble in that time/frequency slot anduse the corresponding DL beam when transmitting the RAR. Hence,beam-specific PRACH configurations may allow the gNB to direct its Rxbeamforming in the direction of the same beam when monitoring theassociated PRACH resources.

NR may support the CFRA with one or more RACH resources dedicated forthe CFRA for one or more cases such as handover, DL data arrival,positioning and obtaining timing advance alignment for a secondary TAG.

For the CFRA case, NR may allow a UE to perform multiple RAPtransmissions before the end of a RAR window. A UE may be configured totransmit multiple RAPs over dedicated multiple RACH transmissionoccasions in time domain. For example, a UE may perform the multipleRAPs transmission prior to the end of a monitored RAR window. The timeresource employed for CFRA (e.g., dedicated RACH in time domain forCFRA) may be different from the time resources of CBRA. A UE maytransmit the multiple RAPs with same or different UE TX beams. Based onthe multiple RAP transmissions, a UE and/or gNB without Tx/Rr beamcorrespondence may find to find the Tx/Rx beam correspondence. Themultiple RAP transmission may result in increasing the successprobability of preamble transmission.

A UE may skip one or more RAP transmissions on one or more configuredPRACH radio resources. For example, a UE may determine whether totransmit a RAP on a PRACH radio resource based on a DL measurement onone or more SS blocks and/or CSI-RSs associated with the PRACH radio,e.g., the UE may skip a RAP transmission on a PRACH radio resource if aDL measurement on a SS block associated with the PRACH radio resource isbelow a threshold. The threshold may be predefined by the UE.

In an example, a gNB may configure a threshold limiting a number of RAPtransmissions that a UE may perform before the end of a RAR window. Thethreshold may be predefined. The gNB may transmit the threshold alongwith a RACH configuration for CFRA, e.g., via one or more broadcastmessages, one or more RRC messages dedicated for a UE, or via one ormore PDCCH orders. A UE may perform a number of RAP transmissions untilthe number of RAP transmission is equal to or less than the threshold.The UE may transmit the same or different RAP during the multiple RAPtransmissions depending on the association between RACH transmissionoccasions and RAP indices configured by RACH configuration.

NR may support one or more DL L1/L2 beam management procedurescomprising at least one of P1, P2, or P3 procedure. The P-1 proceduremay enable one or more UE measurements on different TRP Tx beams tosupport a selection of one or more TRP Tx beams and/or one or more UE Rxbeam. Beamforming at TRP may comprise a intra/inter-TRP Tx beam sweepfrom a set of different beams. Beamforming at UE may comprise a UE Rxbeam sweep from a set of different beams. The P-2 procedure may be usedto enable UE measurement on different TRP Tx beams to possibly changeone or more inter/intra-TRP Tx beams from a possibly smaller set ofbeams for beam refinement than in P-1. P-2 may be a special case of P-1.The P-3 procedure may enable one or more UE measurements on a given TRPTx beam to change UE Rx beam in the case a UE employs beamforming. NRmay support at least aperiodic beam reporting under P-1, P-2, and P-3related operations.

In an example, one or more DL beams employed for transmitting one ormore SS blocks may be wide in order to reduce beam sweeping time andsystem overhead. For example, beam sweeping with one or more wide beamsmay be efficient to cover a cell coverage. The gNB may complete beamsweeping with a small number of sweeps by using a wide beam to transmitthe one or more SS blocks in the cell coverage. For example, a wide beammay be efficient for a gNB to transmit a broadcast message to one ormore UEs, for example, for which the gNB does not have channel stateinformation. To transmit a dedicated message to one or more UEs (e.g.,in a small area), a wide beam operation may not be efficient due to alow antenna gain. For example, if a gNB performs a RA procedure with aUE connected to a network, e.g., an RRC connected UE, a UE performing ahandover, and/or adding a secondary cell to a UE, a wide beam operationmay not be efficient. There is a need to improve random access procedureto enhance beam forming operation and increase radio link quality.Example embodiments implements beam refinement processes with a randomaccess procedure to enhance beam forming and radio link quality.

In an example embodiment, if the RA procedure is initiated by a UEconnected to a network (RRC connected UE), the gNB may have channelstate information of channel(s) between the gNB and the UE. For example,a gNB may (periodically, a periodically, and/or semi-persistently)request to a UE to transmit a channel measurements report, e.g., radiolink measurement, and/or CSI-RS report. The gNB may use the channelstate information to form a beam toward the UE with a higher antennagain. The high antenna gain may increase a success rate of detectionand/or decoding probability. For example, the RA procedure with thenarrow beam may increase detection/decoding probability of DL and/or ULtransmissions, which may result in reducing a signaling overhead andpower consumption and may improve radio link quality.

NR may support a beam refinement procedure that may be to refine one ormore DL and/or UL beams for a RA procedure. One or more referencesignals employed for beam identification/refinement may comprise atleast one or more CSI-RS. For example, the one or more CSI-RSs may beperiodic CSI-RSs. In NR, P1 beams (e.g., beams used for SS blocktransmissions) may be at least based on one or more CSI-RSs. A UE may beconfigured time and frequency radio resources, e.g., RACH resources forbeam recovery request transmission, that are associated to one or moreCSI-RSs configured with the UE. Using the association between P1 beamsand CSI-RSs, the UE may request one or more serving beams that may be acomponent beam instead of a composite beam if association was on SSblock.

NR may support a beam refinement procedure during a RA procedure. Forexample, via an RAR, a gNB may configure a UE with one or more CSI-RSresources and antenna ports which may be quasi-co-located (QCL)associated with antenna port of a preferred SS block that the UEindicates via a PRACH preamble selection. In response to receiving theRAR, the UE may measure the configured one or more CSI-RSs resources andmay transmit a measurement report to the gNB with one or more parametersfor indicating which CSI-RS resources and/or beams are preferred. ThegNB may employ the one or more component beams associated with thepreferred CSI-RS resources and/or beams that the UE informs for asubsequent DL transmission, e.g., contention resolution. A gNB maytransmit one or more CSI-RS configurations, e.g. number of antennaports, time-frequency and sequence configuration, as a part of RACHconfiguration in remaining system information (RMSI). Transmitting theone or more CSI-RS configurations in RMSI may reduce the latency since aUE may be a priori aware of the one or more CSI-RS configurationsassociated with a RAR. For example, when the UE detects PDCCH for a RAR,the UE may be configured with one or more CSI-RSs in response todetecting the RAR.

In an example embodiment, a beam refinement procedure may be implementedfor a RA procedure. For example, a gNB and UE may perform the RAprocedure with a narrow beam which is determined from the beamrefinement procedure. For example, for a UE with RRC connected, a gNBmay have channel state information of one or more channels (DL and/orUL) between a gNB and the UE. The channel state information may be usedfor beam refinement procedure to fine a narrow beam for the UE prior tothe RA procedure. The RA procedure with a narrow beam may increasesuccess rates of detection and/or decoding probabilities in DL and ULchannels. A higher antenna gain provided by a narrow beam may enable agNB and/or a UE to save a power consumption and improve radio linkquality.

In an example, a gNB may trigger a beam refinement procedure for a UEconfigured with a CFRA, e.g., for adding a SCell. A UE may measure oneor more SS blocks of SCells and select at least one SS block of the oneor more SS blocks. For example, the UE may select the at least one SSblock whose measurement (e.g., a pathloss) result may be higher than athreshold that may improve a success rate of data decoding/detection atthe UE. The UE may transmit to the gNB one or more RRC messagescomprising one or more parameters for indicating the at least one SSblock. In response to receiving the one or more RRC messages, the gNBmay configure the UE with one or more CSI-RSs representing componentbeams associated with the at least one SS blocks of the SCell via one ormore RRC messages, e.g., RRCConnectionReconfiguration message in LTE. UEmay measure and transmit one or more measurement results of the one ormore configured CSI-RSs to the gNB. In response to receiving themeasurement results, the gNB may transmit at least one DCI to configurethe UE with CFRA on the SCell. The at least one DCI may comprise one ormore parameters and/or fields for indicating at least one of one or moreRAPs, one or more PRACH mask indices, or one or more first CSI-RSselected by the gNB. The gNB may select the one or more first CSI-RS atleast based on the one or more measurement results of the one or moreconfigured CSI-RSs transmitted by the UE to the gNB. The one or morefirst CSI-RSs selected by the gNB may indicate one or more beamsemployed for DL CSI-RS transmission, e.g., one or more gNB's Tx beams,one or more UE's Rx beam, and/or one or more beam pair link of one ormore gNB's Tx beams and one or more UE's Rx beam, that the gNB selectsfor a subsequent UL/DL transmissions. The UE may determine one or moreUE's UL Tx beams at least based on UE's Tx/Rx beam correspondence andthe one or more UE's Rx beams employed for receiving the one or moreCSI-RS selected by the gNB. The UE may transmit the one or more RAPsemploying the one or more determined UE's Tx beams for the configuredCFRA. The RA procedure with a narrow beam may increase success rates ofdetection and/or decoding probabilities in DL and UL channels. A higherantenna gain provided by a narrow beam may enable a gNB and/or a UE tosave a power consumption and improve radio link quality.

FIG. 24 shows an example of a beam refinement procedure. For example, agNB may transmit one or more SS blocks with one or more DL Tx beams. AUE may be configured, by the gNB, to measure the one or more SS blocksperiodically (semi-persistently, and/or based upon a request of radioresource measurement report). The UE may measure the one or more SSblocks and transmit the measurement results of the one or more SS blocksto the gNB. The measurement results may comprise at least one offollowing: one or more received signal strength of the one or more SSblocks, one or more preferred DL Tx beam indices, and one or morepreferred SS block indices. The gNB may select at least one DL Tx beam(equivalently at least one SS block) based at least on the measurementresults, e.g., as a preferred beam. The gNB may configure, based atleast on the measurement results, the UE with one or more CSI-RS sassociated with the at least one DL Tx beam. For example, antennaport(s) of the one or more CSI-RSs may be QCLed with antenna port(s) ofthe at least one DL Tx beam (equivalently at least one SS block). ThegNB may configure the UE to transmit a measurement report of the one ormore CSI-RSs. In response to the UE transmitting the measurement report,the gNB may select at least one DL Tx narrow beam (equivalently at leastone CSI-RS) based at least on the measurement results, e.g., as apreferred narrow beam. The gNB may transmit, to the UE, a messagingindicating random access configuration parameters comprising theselected CSI-RS. For example, the message may be an RRC message. The gNBmay initiate a random access procedure, e.g., for a SCell addition. TheSCell addition may be initiated by a PDCCH order transmitted by the gNBto the UE. In response to receiving the PDCCH order, the UE may performthe random access procedure based on the selected CSI-RS.

In an example, a gNB in NR may trigger a beam refinement procedure for aUE configured with a CFRA for adding a SCell. A UE may measure one ormore SS blocks of SCells and select at least one SS block of the one ormore SS blocks. For example, the UE may select the at least one SS blockwhose measurement result may be higher than a threshold that may improvea success rate of data decoding/detection at the UE. The UE may transmitto the gNB one or more RRC messages comprising one or more parametersfor indicating the at least one SS block. In response to receiving theat least one SS block selected by the UE, the gNB may transmit one ormore first RRC messages to configure the UE to add the SCell. The one ormore first RRC messages may configure the UE with one or more CSI-RSresources and antenna ports which may be QCL associated with one or moreSS blocks configured on the SCell. The one or more first RRC messagesmay indicate when to start DL measurements on the one or more CSI-RSresources. The one or more first RRC messages may comprise anassociation between the one or more CSI-RS resources and antenna portsand the one or more SS blocks configured on the SCell. The one or morefirst RRC messages may comprise one or more parameters for indicating anassociation between the one or more CSI-RS resources and antenna portsand RACH resources configured on the SCell. The UE may measure the oneor more CSI-RS and select at least one of the one or more CSI-RSsconfigured by the gNB at least based on measurements of the receivedsignal strength of the one or more CSI-RSs configured by the gNB. ThegNB may transmit at least one DCI to configure the UE with CFRA on theSCell. The at least one DCI may comprise one or more parameters and/orfields for indicating at least one of one or more RAPs, one or morePRACH mask indices. The UE may select at least one RAP of the at leastone of one or more RAPs and at least one PRACH radio resource totransmit the at least one RAP based on at least one of the one or morefirst RRC messages and the at least one of CSI-RS selected by the UE.The UE may transmit to the gNB the at least one RAP via the at least onePRACH radio resource. The gNB may transmit one or more RARs in responseto receiving the at least one RAP from the UE. In response to receivingthe one or more RARs, the UE may determine one or more UE's UL Tx beamsat least based on UE's Tx/Rx beam correspondence and one or more UE's Rxbeams employed for receiving the at least one of CSI-RS selected by theUE for a subsequent transmission.

FIG. 25 is an example of a beam refinement procedure, for example, foran SCell addition. For example, a gNB may transmit one or more SS blockswith one or more DL Tx beams. A UE may be configured, by the gNB, tomeasure the one or more SS blocks periodically (semi-persistently,and/or based upon a request of radio resource measurement report). TheUE may measure the one or more SS blocks and transmit the measurementresults of the one or more SS blocks to the gNB. The measurement resultsmay comprise at least one of following: one or more received signalstrength of the one or more SS blocks, one or more preferred DL Tx beamindices, and one or more preferred SS block indices. The gNB may selectat least one DL Tx beam (equivalently at least one SS block) based atleast on the measurement results, e.g., as a preferred beam. The gNB mayconfigure, based at least on the measurement results, the UE with one ormore CSI-RSs associated with the at least one DL Tx beam. For example,antenna port(s) of the one or more CSI-RSs may be QCLed with antennaport(s) of the at least one DL Tx beam (equivalently at least one SSblock). The gNB may transmit, to the UE, an RRC message comprisingconfiguration parameters of SCell addition. The RRC message may comprisethe configuration parameters of the one or more CSI-RSs. The gNB maytransmit the one or more CSI-RSs to the UE according to theconfiguration parameters. The one or more CSI-RSs may be periodic, aperiodic or semi-persistent. For the SCell addition, the gNB maytransmit a control message, e.g., PDCCH order, via a PDCCH to initiatethe SCell addition. The control message may comprise at least one RAPthat the UE transmits, to the gNB, during a RA procedure initiated forthe SCell addition. The UE may measure the one or more CSI-RSs and mayselect at least one PRACH occasion. For example, the at least one PRACHoccasion may be associated with one of the one or more CSI-RSs. Forexample, a pathloss measurement of the one of the one or more CSI-RSsmay be equal to or larger than a threshold configured by the gNB. Forexample, a pathloss measurement of the one of the one or more CSI-RSsmay be the highest among pathloss measurements of the one or moreCSI-RSs. The association between the one or more CSI-RSs and one or morePRACH occasions may be explicitly configured by an RRC message. Theassociation between the one or more CSI-RSs and one or more PRACHoccasions may be implicitly configured by an RRC message. For example,the UE may identify the association based on: an association between theone or more SS blocks and one or more PRACH occasions and aQCLed-association between the one or more SS blocks and the one or moreCSI-RSs. For example, the UE may identify the at least one PRACHoccasion based on a first association between a first PRACH occasion anda first SS block that is QCLed with the one of the one or more CSI-RSs.The SCell addition may be initiated by a PDCCH order transmitted by thegNB to the UE. In response to receiving the PDCCH order, the UE mayperform the random access procedure by transmitting the at least one RAPvia the first PRACH occasion associated with the one of the one or moreCSI-RSs.

In an example, a wireless device may measure a received signal strengthof at least one synchronization signal (SS) block configured on asecondary cell (SCell). The wireless device may transmit to a basestation, one or more measurement reports comprising one or moreparameters for indicating at least one SS block selected by the wirelessdevice. The wireless device may receive from the base station, at leastone radio resource control (RRC) message for the SCell, wherein the atleast one RRC message may comprise one or more parameters for indicatingat least one channel state information reference signals (CSI-RSs)determined at least based on the at least one selected SS block. Thewireless device may transmit to a base station, one or more measurementreports comprising one or more parameters for indicating at least oneCSI-RS selected by the wireless device. The wireless device may receivefrom the base station via one or more control channels, at least onedownlink control information, wherein at least one downlink controlinformation may comprise one or more parameters for indicating at leastone of indication of at least one CSI-RS selected by the gNB, one ormore RAPs, or one or more random access channels. The wireless devicemay transmit to the SCell, the at least one of the one or more RAPs viaat least one of the one or more random access channels via at least oneTx beam corresponding to at least one Rx beam employed for receiving oneor more CSI-RSs associated with the indication of at least one CSI-RSselected by the gNB.

In an example, the base station may transmit, to the wireless device viathe SCell, the at least one SS block. In an example, the one or moremeasurement reports on the at least one SS block may comprise at leastone of at least one index for indicating the at least one SS blockselected by the wireless device or at least one index for indicating areceived signal strength of the at least one SS block selected by thewireless device. In an example, the one or more measurement reports onthe at least one CSI-RS may comprise at least one of at least one indexfor indicating the at least one CSI-RS selected by the wireless deviceor at least one index for indicating a received signal strength of theat least CSI-RS selected by the wireless device. In an example, theindication of at least one CSI-RS selected by the gNB may be determinedat least based on the one or more parameters for indicating at least oneCSI-RS selected by the wireless device.

According to various embodiments, a device such as, for example, awireless device, a base station, base station central unit, a basestation distributed unit, a core network entity, and/or the like, maycomprise one or more processors and memory. The memory may storeinstructions that, when executed by the one or more processors, causethe device to perform a series of actions. Embodiments of exampleactions may be illustrated in the accompanying figures andspecification. Features from various embodiments may be combined tocreate yet further embodiments.

FIG. 26 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 2610, a base station may transmit to awireless device, a first request to measure one or more synchronizationsignals of a first cell. At 2620, the base station may receive from thewireless device, at least one first measurement report of at least onesynchronization signal of the one or more synchronization signals. At2630, the base station may transmit to the wireless device, a secondrequest to measure one or more channel state information referencesignals (CSI-RSs) of the first cell. At 2640, the base station mayreceive from the wireless device, at least one second measurement reportof the one or more CSI-RSs. The at least one second measurement reportmay be generated in response to the second request. At 2650, the basestation may select at least one first CSI-RS of the one or more CSI-RSbased on the at least one second measurement report. At 2660, the basestation may transmit to the wireless device via one or more controlchannels, a downlink control information initiating a random accessprocedure of the first cell. The downlink control information maycomprise an indication of the at least one first CSI-RS.

According to an embodiment, the first cell may be a secondary cell.According to an embodiment, the one or more first measurement reportsmay indicate at least one first index of the at least onesynchronization signal. According to an embodiment, the one or morefirst measurement reports may indicate at least one first receivedsignal strength of the at least one synchronization signal. According toan embodiment, the one or more second measurement reports may indicateat least one second index of a second CSI-RS selected by the wirelessdevice among the one or more CSI-RSs. According to an embodiment, theone or more second measurement reports may indicate at least one secondreceived signal strength of the second CSI-RS. According to anembodiment, the base station may transmit the one or moresynchronization signals to the wireless device via the first cell.According to an embodiment, each of the one or more synchronizationsignals may comprise a primary synchronization signal and a secondarysynchronization signal. According to an embodiment, the secondarysynchronization signal may indicate a cell identifier of the first cell.According to an embodiment, each of the one or more synchronizationsignals may comprise a tertiary synchronization signal. According to anembodiment, the primary synchronization signal and the secondarysynchronization signal may be time division multiplexed with a physicalbroadcast channel. According to an embodiment, the primarysynchronization signal may be a Zadoff-Chu sequence. According to anembodiment, the downlink control information may comprise at least onerandom access preamble. According to an embodiment, the base station mayreceive from the wireless device, the at least one random accesspreamble via one or more random access channel of the first cell.According to an embodiment, the base station may transmit to thewireless device, at least one random access response in response to theat least one random access preamble. According to an embodiment, the atleast one random access response may be scrambled by a random accessradio network temporary identifier. According to an embodiment, the atleast one random access response may comprise a timing advance command.According to an embodiment, the at least one random access response maycomprise an uplink grant. According to an embodiment, the downlinkcontrol information may be scrambled by a cell radio network temporaryidentifier. According to an embodiment, the one or more channel stateinformation reference signals (CSI-RSs) may be periodic CSI-RSs.According to an embodiment, a first antenna port of one or more CSI-RSsof the first cell may be quasi-colocated with a second port of the atleast one synchronization signal.

FIG. 27 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 2710, a wireless device may receive from abase station, a first request to measure one or more synchronizationsignals of a first cell. At 2720, the wireless device may transmit tothe base station, at least one first measurement report of at least onesynchronization signal of the one or more synchronization signals. At2730, the wireless device may receive from the base station, a secondrequest to measure one or more channel state information referencesignals (CSI-RSs) of the first cell. At 2740, the wireless device maytransmit to the base station, at least one second measurement report ofthe one or more CSI-RSs, the at least one second measurement reportgenerated in response to the second request. At 2750, the wirelessdevice may receive from the base station via one or more controlchannels, a downlink control information initiating a random accessprocedure of the first cell. The downlink control information maycomprise an indication of the at least one first CSI-RS. At least onefirst CSI-RS of the one or more CSI-RS may be selected by the basestation based on the at least one second measurement report.

According to an embodiment, the first cell may be a secondary cell.According to an embodiment, the one or more first measurement reportsmay indicate at least one first index of the at least onesynchronization signal. According to an embodiment, the one or morefirst measurement reports may indicate at least one first receivedsignal strength of the at least one synchronization signal. According toan embodiment, the one or more second measurement reports may indicateat least one second index of a second CSI-RS selected by the wirelessdevice among the one or more CSI-RSs. According to an embodiment, theone or more second measurement reports may indicate at least one secondreceived signal strength of the second CSI-RS. According to anembodiment, the one or more synchronization signals may be received,from the base station transmits, via the first cell. According to anembodiment, each of the one or more synchronization signals may comprisea primary synchronization signal and a secondary synchronization signal.According to an embodiment, the secondary synchronization signal mayindicate a cell identifier of the first cell. According to anembodiment, each of the one or more synchronization signals may comprisea tertiary synchronization signal. According to an embodiment, theprimary synchronization signal and the secondary synchronization signalmay be time division multiplexed with a physical broadcast channel.According to an embodiment, the primary synchronization signal may be aZadoff-Chu sequence. According to an embodiment, the downlink controlinformation may comprise at least one random access preamble. Accordingto an embodiment, the wireless device may transmit to the base station,the at least one random access preamble via one or more random accesschannel of the first cell. According to an embodiment, the wirelessdevice may receive from the base station, at least one random accessresponse in response to the at least one random access preamble.According to an embodiment, the at least one random access response maybe scrambled by a random access radio network temporary identifier.According to an embodiment, the at least one random access response maycomprise a timing advance command. According to an embodiment, the atleast one random access response may comprise an uplink grant. Accordingto an embodiment, the downlink control information may be scrambled by acell radio network temporary identifier. According to an embodiment, theone or more channel state information reference signals (CSI-RSs) may beperiodic CSI-RSs. According to an embodiment, a first antenna port ofone or more CSI-RSs of the first cell may be quasi-colocated with asecond port of the at least one synchronization signal.

FIG. 28 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 2810, a base station may transmit to awireless device, a first request to measure one or more synchronizationsignals of a first cell. At 2820, the base station may receive from thewireless device, at least one first measurement report of at least onesynchronization signal of the one or more synchronization signals. At2830, the base station may transmit at least one radio resource controlmessage to the wireless device. The at least one radio resource controlmessage may indicate radio resource parameters of one or more channelstate information reference signals (CSI-RSs) of the first cell. TheCSI-RSs may be determined based on the at least one synchronizationsignal. The at least one radio resource control message may indicateeach of the one or more CSI-RSs corresponds to at least one randomaccess channel of the first cell. At 2840, the base station may transmitthe one or more CSI-RSs to the wireless device. At 2850, the basestation may transmit to the wireless device via one or more controlchannels, a downlink control information indicating at least one randomaccess preamble. At 2860, the base station may receive from the wirelessdevice, the at least one random access preamble via one of the at leastone random access channel corresponding to at least one of the one ormore CSI-RSs.

According to an embodiment, a first antenna port of one or more channelstate information reference signals (CSI-RSs) of the first cell may bequasi-colocated with a second port of the at least one synchronizationsignal. According to an embodiment, the first cell may be a secondarycell. According to an embodiment, the one or more first measurementreports may indicate at least one first index of the at least onesynchronization signal. According to an embodiment, the one or morefirst measurement reports may indicate at least one first receivedsignal strength of the at least one synchronization signal. According toan embodiment, the one or more second measurement reports may indicateat least one second index of a second CSI-RS selected by the wirelessdevice among the one or more CSI-RSs. According to an embodiment, theone or more second measurement reports may indicate at least one secondreceived signal strength of the second CSI-RS. According to anembodiment, the base station may transmit the one or moresynchronization signals to the wireless device via the first cell.According to an embodiment, each of the one or more synchronizationsignals may comprise a primary synchronization signal and a secondarysynchronization signal. According to an embodiment, the secondarysynchronization signal may indicate a cell identifier of the first cell.According to an embodiment, the primary synchronization signal and thesecondary synchronization signal may be time division multiplexed with aphysical broadcast channel. According to an embodiment, the primarysynchronization signal may be a Zadoff-Chu sequence. According to anembodiment, the downlink control information may comprise at least onerandom access preamble. According to an embodiment, the base station mayreceive from the wireless device, the at least one random accesspreamble via one or more random access channels of the first cell.According to an embodiment, the base station may transmit to thewireless device, at least one random access response in response to theat least one random access preamble. According to an embodiment, the atleast one random access response may be scrambled by a random accessradio network temporary identifier. According to an embodiment, the atleast one random access response may comprise a timing advance command.According to an embodiment, the at least one random access response maycomprise an uplink grant. According to an embodiment, the downlinkcontrol information may be scrambled by a cell radio network temporaryidentifier. According to an embodiment, the one or more channel stateinformation reference signals (CSI-RSs) may be periodic CSI-RSs.According to an embodiment, the random access procedure may be acontention free random access procedure.

FIG. 29 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 2910, a wireless device may receive from abase station, a first request to measure one or more synchronizationsignals of a first cell. At 2920, the wireless device may transmit tothe base station, at least one first measurement report of at least onesynchronization signal of the one or more synchronization signals. At2930, the wireless device may receive at least one radio resourcecontrol message from the base station. The at least one radio resourcecontrol message may indicate radio resource parameters of one or morechannel state information reference signals (CSI-RSs) of the first cell.The CSI-RSs may be determined based on the at least one synchronizationsignal. The at least one radio resource control message may indicateeach of the one or more CSI-RSs corresponds to at least one randomaccess channel of the first cell. At 2940, the wireless device mayreceive from the base station, the one or more CSI-RSs. At 2950, thewireless device may receive from the base station via one or morecontrol channels, a downlink control information indicating at least onerandom access preamble. At 2960, the wireless device may transmit to thebase station, the at least one random access preamble via one of the atleast one random access channel corresponding to at least one of the oneor more CSI-RSs.

According to an embodiment, a first antenna port of one or more channelstate information reference signals (CSI-RSs) of the first cell may bequasi-colocated with a second port of the at least one synchronizationsignal. According to an embodiment, the first cell may be a secondarycell. According to an embodiment, the one or more first measurementreports may indicate at least one first index of the at least onesynchronization signal. According to an embodiment, the one or morefirst measurement reports may indicate at least one first receivedsignal strength of the at least one synchronization signal. According toan embodiment, the one or more second measurement reports may indicateat least one second index of a second CSI-RS selected by the wirelessdevice among the one or more CSI-RSs. According to an embodiment, theone or more second measurement reports may indicate at least one secondreceived signal strength of the second CSI-RS. According to anembodiment, the wireless device may receive the one or moresynchronization signals from the base station via the first cell.According to an embodiment, each of the one or more synchronizationsignals may comprise a primary synchronization signal and a secondarysynchronization signal. According to an embodiment, the secondarysynchronization signal may indicate a cell identifier of the first cell.According to an embodiment, the primary synchronization signal and thesecondary synchronization signal may be time division multiplexed with aphysical broadcast channel. According to an embodiment, the primarysynchronization signal may be a Zadoff-Chu sequence. According to anembodiment, the downlink control information may comprise at least onerandom access preamble. According to an embodiment, the wireless devicemay transmit to the base station, the at least one random accesspreamble via one or more random access channels of the first cell.According to an embodiment, the wireless device may receive from thebase station, at least one random access response in response to the atleast one random access preamble. According to an embodiment, the atleast one random access response may be scrambled by a random accessradio network temporary identifier. According to an embodiment, the atleast one random access response may comprise a timing advance command.According to an embodiment, the at least one random access response maycomprise an uplink grant. According to an embodiment, the downlinkcontrol information may be scrambled by a cell radio network temporaryidentifier. According to an embodiment, the one or more channel stateinformation reference signals (CSI-RSs) may be periodic CSI-RSs.According to an embodiment, the random access procedure may be acontention free random access procedure.

In this specification, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” In this specification,the term “may” is to be interpreted as “may, for example.” In otherwords, the term “may” is indicative that the phrase following the term“may” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.If A and B are sets and every element of A is also an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}.

In this specification, parameters (Information elements: IEs) maycomprise one or more objects, and each of those objects may comprise oneor more other objects. For example, if parameter (IE) N comprisesparameter (IE) M, and parameter (IE) M comprises parameter (IE) K, andparameter (IE) K comprises parameter (information element) J, then, forexample, N comprises K, and N comprises J. In an example embodiment,when one or more messages comprise a plurality of parameters, it impliesthat a parameter in the plurality of parameters is in at least one ofthe one or more messages, but does not have to be in each of the one ormore messages.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an isolatableelement that performs a defined function and has a defined interface toother elements. The modules described in this disclosure may beimplemented in hardware, software in combination with hardware,firmware, wetware (i.e hardware with a biological element) or acombination thereof, all of which are behaviorally equivalent. Forexample, modules may be implemented as a software routine written in acomputer language configured to be executed by a hardware machine (suchas C, C++, Fortran, Java, Basic, Matlab or the like) or amodeling/simulation program such as Simulink, Stateflow, GNU Octave, orLabVIEWMathScript. Additionally, it may be possible to implement modulesusing physical hardware that incorporates discrete or programmableanalog, digital and/or quantum hardware. Examples of programmablehardware comprise: computers, microcontrollers, microprocessors,application-specific integrated circuits (ASICs); field programmablegate arrays (FPGAs); and complex programmable logic devices (CPLDs).Computers, microcontrollers and microprocessors are programmed usinglanguages such as assembly, C, C++ or the like. FPGAs, ASICs and CPLDsare often programmed using hardware description languages (HDL) such asVHSIC hardware description language (VHDL) or Verilog that configureconnections between internal hardware modules with lesser functionalityon a programmable device. Finally, it needs to be emphasized that theabove mentioned technologies are often used in combination to achievethe result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the spirit and scope. After reading the abovedescription, it will be apparent to one skilled in the relevant art(s)how to implement alternative embodiments. Thus, the present embodimentsshould not be limited by any of the above described exemplaryembodiments. In particular, it should be noted that, for examplepurposes, the above explanation has focused on the example(s) using FDDcommunication systems. However, one skilled in the art will recognizethat embodiments of the disclosure may also be implemented in a systemcomprising one or more TDD cells (e.g. frame structure 2 and/or framestructure 3-licensed assisted access). The disclosed methods and systemsmay be implemented in wireless or wireline systems. The features ofvarious embodiments presented in this disclosure may be combined. One ormany features (method or system) of one embodiment may be implemented inother embodiments. Only a limited number of example combinations areshown to indicate to one skilled in the art the possibility of featuresthat may be combined in various embodiments to create enhancedtransmission and reception systems and methods.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112. Claims that do not expressly include the phrase “means for”or “step for” are not to be interpreted under 35 U.S.C. 112.

What is claimed is:
 1. A method comprising: receiving, by a base stationfrom a wireless device, at least one first measurement report of atleast one synchronization signal of a cell; selecting one or morechannel state information reference signals (CSI-RSs) of the cell basedon: the at least one first measurement report; and a first antenna portof the one or more CSI-RSs being quasi-collocated with a second port ofthe at least one synchronization signal; receiving at least one secondmeasurement report of the one or more CSI-RSs; selecting, based on theat least one second measurement report, at least one first CSI-RS of theone or more CSI-RSs; and transmitting a downlink control informationinitiating a random access procedure of the cell, the random accessprocedure being based on the at least one first CSI-RS.
 2. The method ofclaim 1, wherein the cell is a secondary cell.
 3. The method of claim 1,wherein the at least one first measurement report indicates at least onefirst index of the at least one synchronization signal.
 4. The method ofclaim 1, wherein the at least one first measurement report indicates atleast one first received signal strength of the at least onesynchronization signal.
 5. The method of claim 1, wherein the at leastone second measurement report indicates at least one second index of asecond CSI-RS selected by the wireless device among the one or moreCSI-RSs.
 6. The method of claim 5, wherein the at least one secondmeasurement report indicates at least one second received signalstrength of the second CSI-RS.
 7. The method of claim 1, wherein thebase station transmits, to the wireless device via the cell, the one ormore synchronization signal.
 8. The method of claim 7, wherein each ofthe one or more synchronization signal comprises a primarysynchronization signal and a secondary synchronization signal.
 9. Themethod of claim 1, wherein the downlink control information furthercomprises at least one random access preamble.
 10. The method of claim1, wherein the downlink control information is scrambled by a cell radionetwork temporary identifier.
 11. A base station comprising: one or moreprocessors; and memory storing instructions that, when executed by theone or more processors, cause the base station to: receive, by a basestation from a wireless device, at least one first measurement report ofat least one synchronization signal of a cell; select one or morechannel state information reference signals (CSI-RSs) of the cell basedon: the at least one first measurement report; and a first antenna portof the one or more CSI-RSs being quasi-collocated with a second port ofthe at least one synchronization signal; receive at least one secondmeasurement report of the one or more CSI-RSs; select, based on the atleast one second measurement report, at least one first CSI-RS of theone or more CSI-RSs; and transmit a downlink control informationinitiating a random access procedure of the cell, the random accessprocedure being based on the at least one first CSI-RS.
 12. The basestation of claim 11, wherein the cell is a secondary cell.
 13. The basestation of claim 11, wherein the at least one first measurement reportindicates at least one first index of the at least one synchronizationsignal.
 14. The base station of claim 11, wherein the at least one firstmeasurement report indicates at least one first received signal strengthof the at least one synchronization signal.
 15. The base station ofclaim 11, wherein the at least one second measurement report indicatesat least one second index of a second CSI-RS selected by the wirelessdevice among the one or more CSI-RSs.
 16. The base station of claim 15,wherein the at least one second measurement report indicates at leastone second received signal strength of the second CSI-RS.
 17. The basestation of claim 11, wherein the instructions, when executed by the oneor more processors, further cause the base station to transmit, to thewireless device via the cell, the one or more synchronization signal.18. The base station of claim 17, wherein each of the one or moresynchronization signal comprises a primary synchronization signal and asecondary synchronization signal.
 19. The base station of claim 11,wherein the downlink control information further comprises at least onerandom access preamble.
 20. A system comprising: a wireless device; anda base station comprising: one or more processors; and memory storinginstructions that, when executed by the one or more processors, causethe base station to: receive, by a base station from the wirelessdevice, at least one first measurement report of at least onesynchronization signal of a cell; select one or more channel stateinformation reference signals (CSI-RSs) of the cell based on: the atleast one first measurement report; and a first antenna port of the oneor more CSI-RSs being quasi-collocated with a second port of the atleast one synchronization signal; receive at least one secondmeasurement report of the one or more CSI-RSs; select, based on the atleast one second measurement report, at least one first CSI-RS of theone or more CSI-RSs; and transmit a downlink control informationinitiating a random access procedure of the cell, the random accessprocedure being based on the at least one first CSI-RS.